Per-endpoint rate limits are too restrictive for AI agent workflows and not configurable

Problem Outline's per-endpoint rate limits are hard-coded in the route definitions and cannot be adjusted by self-hosted operators. The global rate limiter has environment variables (RATE_LIMITER_REQUESTS, RATE_LIMITER_DURATION_WINDOW), but per-endpoint overrides ignore these and use fixed values from RateLimiterStrategy. This is increasingly a problem as AI agents become a primary API consumer — a use case Outline is actively embracing with the built-in MCP server (v1.6.0). A single logical agent operation like "review a document and post feedback" can involve a burst of API calls that exceeds these limits. For example, comments.create is capped at 10 requests per minute. An agent posting 11 comments on a document review hits 429 on the 11th call. The MCP endpoint itself allows 1,000 requests/hour, but the underlying API routes it calls have their own stricter limits — so the MCP rate limit is misleading. This was also raised in [Discussion #6458]( where a …