deps: everything to latest stable

Python 3.12 -> 3.14, postgres 16 -> 18, uv 0.5.11 -> 0.11.29,
trivy 0.58.1 -> 0.72.0, gitleaks 8.21.2 -> 8.30.1, yq 4.44.6 -> 4.53.3,
and every action re-pinned to the SHA of its latest tag (checkout v7,
setup-uv v8, buildx v4, login v4, hadolint v3.3.0). helm stays 3.21.3:
already current for 3.x, and helm 4 is a breaking change, not a CVE fix.

trivy mattered most. A vulnerability scanner fourteen minor versions behind is
the one stale pin that hides all the others.

ruff target-version is deliberately py313 while the runtime is 3.14. It
controls the syntax the formatter may emit, and at py314 it rewrites
'except (A, B):' into PEP 758's unparenthesized form — which reads exactly
like Python 2's 'except E, name:' and is a hard SyntaxError below 3.14. No
semantic gain, real readability cost, in a repo meant to be read.

Verified on 3.14: ruff, ruff format, mypy --strict, 166 tests, helm lint,
bandit, pip-audit. The digest guard still rejects placeholder digests.

Risk carried knowingly: the bumped actions run on node24. If act_runner only
provides node20, every job fails at action startup and this commit is the
revert.

tests/integration/conftest.py

@@ -9,7 +9,7 @@ Two ways to get a database, in priority order:
 1. `SVCFORGE_TEST_DSN` in the environment — an already-running Postgres. This is the
    path on a host that has no Docker daemon (for example one whose containerd belongs
    to a Kubernetes kubelet, where installing Docker would evict the runtime).
-2. testcontainers, which starts `postgres:16-alpine` and throws it away after. This is
+2. testcontainers, which starts `postgres:18-alpine` and throws it away after. This is
    the CI path.
 
 Same tests either way.
@@ -88,7 +88,7 @@ def pg_dsn() -> Iterator[str]:
         pytest.skip("set SVCFORGE_TEST_DSN or install testcontainers")
 
     # A container is already private to this process; no need to clone inside it.
-    with PostgresContainer("postgres:16-alpine", driver=None) as pg:
+    with PostgresContainer("postgres:18-alpine", driver=None) as pg:
         dsn = pg.get_connection_url()
         _apply_migrations(dsn)
         yield dsn