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

templates/http/Dockerfile

@@ -14,4 +14,13 @@ COPY entrypoint.sh /entrypoint.sh
 RUN chmod +x /entrypoint.sh
 
 EXPOSE 80 443
+RUN useradd -r -s /bin/false -d /opt decnet \
+ && apt-get update && apt-get install -y --no-install-recommends libcap2-bin \
+ && rm -rf /var/lib/apt/lists/* \
+ && find /usr/bin/python3* -maxdepth 0 -type f -exec setcap 'cap_net_bind_service+eip' {} \;
+
+HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
+  CMD kill -0 1 || exit 1
+
+USER decnet
 ENTRYPOINT ["/entrypoint.sh"]