feat(phase-34): resolve blocking tech debt — Redis, domain exceptions, indexes, CI

Foundational changes required before any new feature work can begin.

- 0.1 Redis infrastructure: add redis:7-alpine to docker-compose dev and prod,
  REDIS_URL config, singleton client in app/infrastructure/redis_client.py
- 0.2 Token blacklist on Redis SEC-001: replace in-memory dict with Redis SETEX
  keyed by jti, auto-expiring TTL derived from token exp
- 0.3 Database indexes SR-006: Alembic migration b019 with 5 composite indexes
  for scoring, MTTD/MTTR, remediation, and notification queries
- 0.4 Domain exceptions TD-003: app/domain/exceptions.py with typed errors,
  error_handler middleware mapping them to HTTP, services decoupled from FastAPI
- 0.5 Fix silenced exceptions TD-007: replace 4 bare except-pass blocks in
  test_workflow_service with logger.warning with exc_info
- 0.6 CI pipeline TD-009: GitHub Actions workflow with Postgres and Redis
  service containers, ruff lint, pytest; ruff.toml for baseline config

backend/app/services/campaign_service.py

@@ -8,9 +8,9 @@ import logging
 import uuid
 from datetime import datetime
 
-from fastapi import HTTPException
 from sqlalchemy.orm import Session
 
+from app.domain.exceptions import EntityNotFoundError, InvalidOperationError
 from app.models.campaign import Campaign, CampaignTest, KILL_CHAIN_PHASES
 from app.models.test import Test
 from app.models.test_template import TestTemplate
@@ -49,7 +49,7 @@ def validate_no_circular_dependency(
 ) -> None:
     """Walk the depends_on chain and verify no cycle is formed.
 
-    Raises HTTPException(400) if a circular dependency is detected.
+    Raises :class:`InvalidOperationError` if a circular dependency is detected.
     """
     if depends_on_id is None:
         return
@@ -59,9 +59,8 @@ def validate_no_circular_dependency(
 
     while current is not None:
         if current in visited or current == test_id:
-            raise HTTPException(
-                status_code=400,
-                detail="Circular dependency detected in campaign test chain",
+            raise InvalidOperationError(
+                "Circular dependency detected in campaign test chain"
             )
         visited.add(current)
         parent = db.query(CampaignTest).filter_by(id=current).first()
@@ -119,7 +118,7 @@ def generate_campaign_from_threat_actor(
     """
     actor = db.query(ThreatActor).filter(ThreatActor.id == actor_id).first()
     if not actor:
-        raise HTTPException(status_code=404, detail="Threat actor not found")
+        raise EntityNotFoundError("ThreatActor", str(actor_id))
 
     # Get unvalidated techniques for this actor
     gap_techniques = (
@@ -132,9 +131,8 @@ def generate_campaign_from_threat_actor(
     )
 
     if not gap_techniques:
-        raise HTTPException(
-            status_code=400,
-            detail=f"No uncovered techniques found for {actor.name}",
+        raise InvalidOperationError(
+            f"No uncovered techniques found for {actor.name}"
         )
 
     # Create the campaign