Detect Google-GeminiNotebook as an AI bot

[eldk]

Description

Google renamed the Google-NotebookLM User-Agent token to Google-GeminiNotebook.

The PHP tracker currently recognizes the former Google-NotebookLM token but does not recognize the new Google-GeminiNotebook token. As a result, MatomoTracker::isUserAgentAIBot() returns false for requests using Google's current User-Agent, and doTrackPageViewIfAIBot() does not track them.

This change:

• adds Google-GeminiNotebook to AI_BOT_USER_AGENT_SUBSTRINGS;
• keeps Google-NotebookLM for backward compatibility during the transition;
• adds test coverage for Google's current full desktop User-Agent;
• adds test coverage confirming that the former Google-NotebookLM token remains supported.

Expected behavior:

Google-GeminiNotebook -> AI bot: true
Google-NotebookLM     -> AI bot: true

No bot-name normalization is required in this repository because isUserAgentAIBot() only returns a boolean. Normalization to the historical Google-NotebookLM name is handled by Matomo core and Device Detector.

Related work:

• Detect Google-GeminiNotebook and retain Google-NotebookLM device-detector#8336
• Detect Google-GeminiNotebook as Google-NotebookLM matomo#24913

Google documentation:

https://developers.google.com/crawling/docs/crawlers-fetchers/google-user-triggered-fetchers#gemini-notebook

Checklist

• [✔] I have understood and reviewed all AI outputs before use
• [✔] All AI instructions respect security, IP, and privacy rules

Review

• [✔] ] [Functional review done](https://developer.matomo.org/guides/pull-request-reviews#functional-review-done)
• [✔] [Potential edge cases thought about](https://developer.matomo.org/guides/pull-request-reviews#potential-edge-cases-thought-about)
• [NA] [Usability review done](https://developer.matomo.org/guides/pull-request-reviews#usability-review-done)
• [✔] [Security review done](https://developer.matomo.org/guides/security-in-piwik#checklist)
• [✔] [Wording review done](https://developer.matomo.org/guides/pull-request-reviews#translations-wording-review-done)
• [✔] [Code review done](https://developer.matomo.org/guides/pull-request-reviews#code-review-done)
• [✔] [Tests were added if useful/possible](https://developer.matomo.org/guides/pull-request-reviews#tests-were-added-if-usefulpossible)
• [✔] [Reviewed for breaking changes](https://developer.matomo.org/guides/pull-request-reviews#reviewed-for-breaking-changes)
• [NA] [Developer changelog updated if needed](https://developer.matomo.org/guides/pull-request-reviews#developer-changelog-updated-if-needed)
• [NA] [New documentation added or existing documentation updated](https://developer.matomo.org/guides/pull-request-reviews#documentation-added-if-needed)

Validation

Unit tests were added for both the current and former User-Agent tokens.

The repository test suite has not yet been run locally.

[sgiehl]

Thanks for the contribution!