docs: [#214] update user documentation for provider selection

[josecelano]

Summary

This PR updates the user documentation to ensure provider selection is well-documented throughout the user-facing documentation, as part of the Hetzner Provider Support epic (#205).

Changes

README.md Fixes

• Fixed broken emoji in roadmap section (� → 🗺️)
• Fixed incorrect E2E test command names (e2e-provision-tests → e2e-provision-and-destroy-tests)
• Updated development status to reflect Hetzner Cloud support as implemented
• Added providers/ directory reference to repository structure
• Updated Next Steps section to reflect that Hetzner implementation is complete

Provider Documentation Integration

• quick-start.md: Added "Choose Your Provider" section before the workflow steps with LXD and Hetzner examples
• commands.md: Added "Provider Configuration" section explaining that all environments require a provider section
• commands/provision.md: Added provider-specific prerequisites and output sections explaining different resources created per provider

Testing

All pre-commit checks pass:

• ✅ 1250 unit tests
• ✅ 4 E2E create tests
• ✅ 4 E2E destroy tests
• ✅ Documentation builds successfully
• ✅ All linting checks pass (markdown, yaml, toml, clippy, rustfmt, shellcheck, cspell)

Related Issues

• Closes Update user documentation for provider selection #214 - Update user documentation for provider selection
• Part of Epic: Add Hetzner Provider Support #205 - Hetzner Provider Support (Phase 1)

Checklist

• I have followed the project conventions in AGENTS.md
• Pre-commit checks pass (./scripts/pre-commit.sh)
• Documentation is clear and follows project style

[josecelano]

ACK b62138e