Add method to track an AI bot request, if the current user agent is a known AI bot

[diosmosis]

Description

Changes:

• Add doTrackPageViewIfAIBot & getUrlTrackAIBot methods for sending AI bot tracking requests server side.
• Add isUserAgentAIBot static method for checking if a user agent matches a known AI bot.

Checklist

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

Review

• Functional review done
• Potential edge cases thought about (behaviour of the code with strange input, with strange internal state or possible interactions with other Matomo subsystems)
• Usability review done (is anything maybe unclear or think about anything that would cause people to reach out to support)
• Security review done
• Wording review done
• Code review done
• Tests were added if useful/possible
• Reviewed for breaking changes
• Developer changelog updated if needed
• New documentation added or existing documentation updated

[diosmosis]

@matomo-org/core-reviewers please review this.

[sgiehl]

AI bot tracking review

Reviewed the branch against what Matomo core (core/Tracker.php) and the BotTracking plugin actually read/expect (cross-checked with two independent passes + the server's own integration tests and BotDetector).

What matches correctly: the recMode=1 semantics (bot-only recording), and the http_status / bw_bytes / pf_srv / source parameter names — all four are read by BotRequestProcessor, and source is genuinely supported (used by VisitorGenerator). 6 of the 7 UA substrings match BotDetector's AI-chatbot patterns exactly.

Blocking / should-fix before merge:

1. Blocker — the unit suite is red: the Devin row still expects true after Devin was removed from the list (inline).
2. Major — GPTBot is in the client list but the server's BotDetector doesn't recognize it, so those requests are accepted but recorded nowhere (silent data loss) (inline).

Minor (worth doing in the same pass, both cause silent data loss): !empty() drops valid 0 telemetry, and source isn't truncated to the server's VARCHAR(50) (inline). Plus PHPDoc/return-contract fixes (inline).

Not inlined (low priority):

• No test exercises doTrackPageViewIfAIBot() itself (matched + unmatched paths), no zero-value boundary test, and there's no positive Google-NotebookLM case in the provider.
• Unrelated indentation churn at lines ~922, ~1427, ~2022 (formatter over-indentation of continuation params) — revert to keep the diff focused.

Inline comments include ready-to-apply suggestions.