chore(msrv): bump workspace rust-version from 1.85 to 1.88

[josecelano]

Closes #1787

Summary

Bumps rust-version in Cargo.toml from 1.85 to 1.88.

Motivation

cargo update with MSRV 1.85 was downgrading already-present packages (bollard,
tonic, testcontainers, serde_with, time, ureq, etc.) because those packages
already in the lockfile require Rust > 1.85. The MSRV-aware resolver (stable
since Rust 1.76) only selects package versions compatible with the declared
rust-version.

A dry-run at 1.86, 1.87, and 1.88 showed that 1.88 is the minimum floor that
produces zero downgrades on the current lockfile. It also aligns with the MSRV
used in torrust-index.

Changes

• Cargo.toml: rust-version = "1.85" → "1.88"
• 5 clippy collapsible_if fixes: let_chains (RFC 2679) was stabilised in
  Rust 1.88, so clippy now expects nested if/if let patterns to be collapsed
  with && let-chain syntax. Fixed in:
  • packages/tracker-core/tests/common/test_env.rs
  • packages/tracker-core/tests/integration.rs
  • packages/udp-tracker-server/src/statistics/event/handler/error.rs
  • src/console/ci/compose.rs
  • src/console/ci/e2e/logs_parser.rs
• AGENTS.md: updated MSRV reference and added MSRV policy note
• .github/skills/dev/maintenance/setup-dev-environment/SKILL.md: updated MSRV reference
• docs/issues/open/1787-evaluate-msrv-bump.md: issue spec marked done, Policy Decision section added
• project-words.txt: added ureq (spell-check dictionary)

Policy Decision

Until the bittorrent-* crates are extracted as standalone libraries (#1669),
a single workspace MSRV applies. Once they are extracted:

• Tracker application (torrust-tracker-*, main binary): track a recent
  stable Rust version.
• bittorrent-* libraries: carry the minimum MSRV needed for external
  consumer compatibility.

A follow-up issue will be opened when #1669 closes to apply the split policy.

[Copilot]

Pull request overview

This PR raises the workspace Minimum Supported Rust Version (MSRV) to Rust 1.88 to prevent MSRV-aware dependency resolution from downgrading already-pinned lockfile dependencies, and updates code/docs accordingly.

Changes:

• Bump workspace rust-version from 1.85 → 1.88.
• Apply clippy-driven collapsible_if refactors using let-chains (now stable with the new MSRV).
• Update MSRV references in documentation and add ureq to the spell-check dictionary.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
Cargo.toml	Bumps workspace rust-version to 1.88 (propagated via workspace.package).
packages/tracker-core/tests/common/test_env.rs	Refactors retry loop condition using let-chains (currently introduces a compile issue).
packages/tracker-core/tests/integration.rs	Collapses nested conditionals into a let-chain in an integration test retry loop.
packages/udp-tracker-server/src/statistics/event/handler/error.rs	Collapses nested conditionals into a let-chain for metrics labeling logic.
src/console/ci/compose.rs	Collapses nested conditionals into a let-chain while waiting for compose port mappings.
src/console/ci/e2e/logs_parser.rs	Collapses nested conditionals into a let-chain when parsing health-check URLs.
AGENTS.md	Updates MSRV reference and adds an MSRV policy note.
.github/skills/dev/maintenance/setup-dev-environment/SKILL.md	Updates MSRV reference in dev environment setup guidance.
docs/issues/open/1787-evaluate-msrv-bump.md	Marks the issue spec as done and records the policy decision/rationale (has internal consistency issues).
project-words.txt	Adds ureq to the project dictionary (kept in sorted order).

Comments suppressed due to low confidence (2)

docs/issues/open/1787-evaluate-msrv-bump.md:140

• The Implementation Plan lists T5 (“Verify CI passes”) as TODO, but the workflow checkpoints below mark “Automatic verification completed” as done. Please make these consistent (either mark T5 as DONE and add evidence, or revert the workflow checkpoint if CI hasn’t been run yet).

| ID  | Status | Task                                                                | Notes / Expected Output                                                                                                                                                                    |
| --- | ------ | ------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| T1  | DONE   | Decide MSRV policy (track latest stable vs. pin conservative floor) | Policy documented in "Policy Decision" section: 1.88 for the whole workspace now; split policy (app tracks latest stable, extracted libraries keep minimum MSRV) to be applied post-#1669. |
| T2  | DONE   | Update `rust-version` in root `Cargo.toml`                          | Changed from `"1.85"` to `"1.88"`                                                                                                                                                          |
| T3  | DONE   | Update `AGENTS.md` MSRV reference                                   | Updated from `1.85` to `1.88`                                                                                                                                                              |
| T4  | DONE   | Update setup-dev-environment SKILL.md MSRV reference                | Updated from `1.85` to `1.88`                                                                                                                                                              |
| T5  | TODO   | Verify CI passes                                                    | Full quality gate (`linter all`, tests, pre-push hook)                                                                                                                                     |

docs/issues/open/1787-evaluate-msrv-bump.md:202

• The Acceptance Verification table marks AC1–AC4 as DONE, but the Acceptance Criteria checklist above (AC1–AC4) remains unchecked. Please update one of these so the spec doesn’t show contradictory completion status.

| AC ID | Status (`TODO`/`DONE`) | Evidence                                                                                                      |
| ----- | ---------------------- | ------------------------------------------------------------------------------------------------------------- |
| AC1   | DONE                   | Policy documented in "Policy Decision" section; split policy for post-extraction recorded as follow-up action |
| AC2   | DONE                   | `rust-version = "1.88"` in `Cargo.toml`                                                                       |
| AC3   | DONE                   | `AGENTS.md` updated to MSRV 1.88                                                                              |
| AC4   | DONE                   | `setup-dev-environment` SKILL.md updated to MSRV 1.88                                                         |
| AC5   | TODO                   |                                                                                                               |
| AC6   | TODO                   |                                                                                                               |
| AC7   | TODO                   |                                                                                                               |

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[josecelano]

ACK 7462511

[codecov]

Codecov Report

❌ Patch coverage is 64.00000% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.70%. Comparing base (e3f6658) to head (7462511).

Files with missing lines	Patch %	Lines
src/console/ci/compose.rs	0.00%	8 Missing ⚠️
...acker-server/src/statistics/event/handler/error.rs	91.66%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #1815   +/-   ##
========================================
  Coverage    77.70%   77.70%           
========================================
  Files          379      379           
  Lines        28607    28605    -2     
  Branches     28607    28605    -2     
========================================
- Hits         22228    22227    -1     
+ Misses        6066     6064    -2     
- Partials       313      314    +1     

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