Add PID-controlled adaptive rate limiting plan for relay operations

- Design comprehensive rate limiting for both reads (REQ) and writes (EVENT)
- Implement PID controller with filtered derivative to avoid noise amplification
- Apply low-pass filter before derivative computation (bandpass effect)
- Add anti-windup for integral term to prevent saturation
- Support setpoint-based control (target operating point as memory fraction)
- Separate tuning parameters for read vs write operations
- Monitor database-specific metrics (Badger LSM, Neo4j transactions)
- Combine memory pressure (70%) and load level (30%) into process variable
- Include integration examples for WebSocket handlers and import loop
- Add configuration via environment variables with sensible defaults

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.claude/settings.local.json

@@ -82,7 +82,9 @@
       "Bash(update-desktop-database:*)",
       "Bash(CGO_ENABLED=0 go build:*)",
       "Bash(CGO_ENABLED=0 go test:*)",
-      "Bash(git submodule:*)"
+      "Bash(git submodule:*)",
+      "WebFetch(domain:neo4j.com)",
+      "Bash(git reset:*)"
     ],
     "deny": [],
     "ask": []