C1: SHA-pin tooling dependencies (2026-04 cycle) (#344)

## Summary

Monthly tooling dependency refresh, with a one-time conversion from version-tag pins (`rev = "vX.Y.Z"`, `image:tag`, `>=`) to SHA / digest pins everywhere.

## Changes

- **prek hooks**: all `rev = "vX.Y.Z"` → commit SHA + `# vX.Y.Z` comment. Bumped trufflehog (3.94.0→3.95.2), kingfisher (1.91.0→1.97.0), ruff (0.15.7→0.15.12), shfmt (3.13.0→3.13.1), prettier (3.8.1→3.8.3), actionlint (1.7.11→1.7.12).
- **fly/Dockerfile**: tag pins → `image@sha256:...` digest pins. Bumped nginx (1.29.6→1.30.0-alpine), tailscale (v1.94.1→v1.94.2 — still inside the safe pre-1.96.5 range), alloy (v1.14.1→v1.16.0).
- **mise-tasks**: PEP 723 inline deps converted from `>=` to `==` (PEP 508 doesn't support hashes inline). All scripts pinned to current latest: rich 15.0.0, typer 0.25.0, pyyaml 6.0.3, httpx 0.28.1.
- **prek `additional_dependencies`**: ansible-lint==26.4.0, ansible-core==2.20.5.
- **taplo-lint**: pass `--no-schema`. Upstream's `--default-schema-catalogs` returns a format taplo v0.9.3 can't parse — we don't validate against TOML schemas anyway, so this turns off the broken catalog fetch.
- **docs/update-tooling-dependencies**: documents the SHA-pin convention, `docker buildx imagetools inspect` for digest lookup, and `prek clean` before re-verifying (cache grows to several GiB).

Forgejo workflow `actions/checkout@v6.0.2` was already at the latest SHA — no change.

## Test plan

- [x] `prek run --all-files` passes after `prek clean`
- [x] `deploy-fly` workflow builds and deploys the new fly image on merge
- [x] `fly status -a blumeops-proxy` healthy after deploy
- [x] Spot-check a few mise tasks (`mise run blumeops-tasks`, `mise run docs-check-links`) to confirm pinned deps resolve cleanly

Reviewed-on: #344

mise-tasks/runner-logs

@@ -1,7 +1,7 @@
 #!/usr/bin/env -S uv run --script
 # /// script
 # requires-python = ">=3.12"
-# dependencies = ["httpx>=0.28.1", "rich>=14.0.0", "typer>=0.24.0"]
+# dependencies = ["httpx==0.28.1", "rich==15.0.0", "typer==0.25.0"]
 # ///
 #MISE description="List recent Forgejo Actions runs or fetch logs for a specific job"
 #USAGE arg "[run_number]" help="Run number to show jobs for (omit to list recent runs)"