fix: clear all addressable technical debt (DEBT-005 through DEBT-025)

Security:
- DEBT-008: remove query-string token auth; header-only Bearer now enforced
- DEBT-013: add regex constraint ^[a-z0-9\-]{1,64}$ on decky_name path param
- DEBT-015: stop leaking raw exception detail to API clients; log server-side
- DEBT-016: validate search (max_length=512) and datetime params with regex

Reliability:
- DEBT-014: wrap SSE event_generator in try/except; yield error frame on failure
- DEBT-017: emit log.warning/error on DB init retry; silent failures now visible

Observability / Docs:
- DEBT-020: add 401/422 response declarations to all route decorators

Infrastructure:
- DEBT-018: add HEALTHCHECK to all 24 template Dockerfiles
- DEBT-019: add USER decnet + setcap cap_net_bind_service to all 24 Dockerfiles
- DEBT-024: bump Redis template version 7.0.12 → 7.2.7

Config:
- DEBT-012: validate DECNET_API_PORT and DECNET_WEB_PORT range (1-65535)

Code quality:
- DEBT-010: delete 22 duplicate decnet_logging.py copies; deployer injects canonical
- DEBT-022: closed as false positive (print only in module docstring)
- DEBT-009: closed as false positive (templates already use structured syslog_line)

Build:
- DEBT-025: generate requirements.lock via pip freeze

Testing:
- DEBT-005/006/007: comprehensive test suite added across tests/api/
- conftest: in-memory SQLite + StaticPool + monkeypatched session_factory
- fuzz mark added; default run excludes fuzz; -n logical parallelism

DEBT.md updated: 23/25 items closed; DEBT-011 (Alembic) and DEBT-023 (digest pinning) remain

decnet/web/api.py

@@ -1,4 +1,5 @@
 import asyncio
+import logging
 from contextlib import asynccontextmanager
 from typing import Any, AsyncGenerator, Optional
 
@@ -10,19 +11,22 @@ from decnet.web.dependencies import repo
 from decnet.web.ingester import log_ingestion_worker
 from decnet.web.router import api_router
 
+log = logging.getLogger(__name__)
 ingestion_task: Optional[asyncio.Task[Any]] = None
 
 
 @asynccontextmanager
 async def lifespan(app: FastAPI) -> AsyncGenerator[None, None]:
     global ingestion_task
-    
-    # Retry initialization a few times if DB is locked (common in tests)
-    for _ in range(5):
+
+    for attempt in range(1, 6):
         try:
             await repo.initialize()
             break
-        except Exception:
+        except Exception as exc:
+            log.warning("DB init attempt %d/5 failed: %s", attempt, exc)
+            if attempt == 5:
+                log.error("DB failed to initialize after 5 attempts — startup may be degraded")
             await asyncio.sleep(0.5)
     
     # Start background ingestion task