API rate limiting on expensive graph endpoints

[askmy-stack]

Background

Identified during OSS audit v2 of cortex.

Problem Statement

No throttling.

Proposed Solution

slowapi on /query /inject.

Acceptance Criteria

• Implementation complete
• Tests pass
• Documented in README or docs/

Files / Modules Affected

api/main.py

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Suggested labels: priority:high, difficulty:intermediate, category:security
Milestone: v2.0-features
OSS Audit: Master Backlog v2