feat: implement Phase 4 enhancements

- Migrate frontend to Alpine.js for reactive state management
- Add source health dashboard in UI and /api/source-health endpoint
- Add event tagging (PATCH /api/events/{id}/tags) and commenting (POST /api/events/{id}/comments)
- Add CSV/JSON export from the UI
- Add rule-based alerting engine (rules.py) with CRUD endpoints (/api/rules)
- Add SIEM export via webhook (siem.py)
- Add AOC audit trail middleware logging all mutations to aoc_audit collection
- Update config with SIEM_ENABLED, SIEM_WEBHOOK_URL, ALERTS_ENABLED
- Add tests for rules engine, tags, comments, and source health

backend/routes/rules.py

@@ -0,0 +1,42 @@
+from auth import require_auth
+from bson import ObjectId
+from fastapi import APIRouter, Depends, HTTPException
+from models.api import AlertRuleResponse
+from rules import rules_collection
+
+router = APIRouter(dependencies=[Depends(require_auth)])
+
+
+def _serialize(doc: dict) -> dict:
+    doc["id"] = str(doc.pop("_id"))
+    return doc
+
+
+@router.get("/rules", response_model=list[AlertRuleResponse])
+def list_rules():
+    return [_serialize(doc) for doc in rules_collection.find()]
+
+
+@router.post("/rules", response_model=AlertRuleResponse)
+def create_rule(rule: AlertRuleResponse):
+    payload = rule.model_dump(exclude={"id"})
+    result = rules_collection.insert_one(payload)
+    payload["id"] = str(result.inserted_id)
+    return payload
+
+
+@router.put("/rules/{rule_id}", response_model=AlertRuleResponse)
+def update_rule(rule_id: str, rule: AlertRuleResponse):
+    payload = rule.model_dump(exclude={"id"})
+    result = rules_collection.update_one({"_id": ObjectId(rule_id)}, {"$set": payload})
+    if result.matched_count == 0:
+        raise HTTPException(status_code=404, detail="Rule not found")
+    return {**payload, "id": rule_id}
+
+
+@router.delete("/rules/{rule_id}")
+def delete_rule(rule_id: str):
+    result = rules_collection.delete_one({"_id": ObjectId(rule_id)})
+    if result.deleted_count == 0:
+        raise HTTPException(status_code=404, detail="Rule not found")
+    return {"deleted": True}