[Gemini Log Analyzer] Part 3: Backend Core (Analyze Logs API & Service)

[ievdokdm]

This is Part 3 of the stacked Pull Request series implementing the Gemini Log Analyzer feature.

Part 1 & Part 2 Backend Infrastructure have been merged! This PR now contains only the core API implementation on top of main.

This PR implements the core backend service and API request handlers for analyzing logs:

• Instantiates the Genkit client and configures plugins (using googleAI) in gae_server.dart.
• Implements LogAnalyzer and its Genkit integration to fetch and parse LUCI build logs.
• Adds the analyze_logs request handler and exposes it as the /api/analyze-logs endpoint.

Stacked PR Series:

• Part 1: Backend Foundation (Models & Setup) (Merged)
• Part 2: Backend Infrastructure (Config & Database Data Flow) (Merged)
• Part 3: Backend Core API (Genkit Logic & Handlers) (This PR)
• Part 4: Frontend Dashboard UI

[eyebrowsoffire]

LGTM