feat(review): inventory and gate REES analyzers

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Summary

Inventory the REES analyzers currently available to Gittensory reviews, document how each is wired, and add explicit enable/disable controls with validation coverage.

Context

REES is only useful operationally if maintainers can tell which analyzers run, what each one costs, how each affects review output, and how to disable noisy or expensive analyzers per repo. The current state needs to be verified from code and runtime behavior rather than assumed.

Requirements

• Identify every REES analyzer currently present, referenced, or expected.
• Determine which analyzers are actually invoked during reviews today.
• Document inputs, outputs, failure behavior, cost/performance impact, and provider dependencies for each analyzer.
• Add per-analyzer enable/disable config if missing.
• Define defaults that are safe for self-hosters.
• Add tests or smoke fixtures proving each analyzer toggle works.

Deliverables

• Analyzer inventory table.
• Config keys and docs for individual analyzer toggles.
• Runtime validation for unknown analyzer names or invalid toggle values.
• Tests covering enabled, disabled, and failure paths.
• Follow-up issues for analyzers that are present but not production-ready.

Acceptance criteria

• A maintainer can tell exactly which REES analyzers ran for a review.
• Analyzer toggles can be set per repo without editing code.
• Tests prove disabled analyzers do not run and enabled analyzers affect review context as expected.