ci: right-size pipelines, fix prerelease latest.json overwrite (#4582)

- build.yml: update latest.json only for stable release tags
  (alpha/beta/rc tags previously overwrote the stable pointer with
  release_type "stable"); drop the placeholder .asc files; build the
  Linux targets only on main pushes (tags/schedule/dispatch keep the
  full matrix); remove the unreachable --build clause and a needless
  full-history clone
- ci.yml: event-scoped concurrency so merges stop cancelling the
  weekly scheduled run; drop the redundant skip-duplicate-actions
  gate job; run clippy before tests; trim the unused toolchain from
  the typos job
- ci-docs-only.yml (new): satisfy the required "Test and Lint" check
  on docs-only PRs that ci.yml skips via paths-ignore
- audit.yml: drop cargo-audit (cargo-deny advisories covers the same
  RustSec database); same event-scoped concurrency fix
- docker.yml: job-level short-circuit for per-merge dev builds; send
  the Trivy SARIF to code scanning; unify the upload-artifact pin
- performance-ab.yml: add concurrency; only re-run on labeled events
  when the added label is perf-ab
- stagger the Sunday crons (build 01:00, audit 03:00,
  nix-flake-update 05:00, mint 06:00)
- delete performance.yml: disabled since 2025-07; idle-server
  profiling, no benchmark baseline, stale ecstore package name

.github/workflows/mint.yml

@@ -50,8 +50,9 @@ on:
         required: false
         default: "minio/mint:edge"
   schedule:
-    # Weekly, after the Sunday s3-tests full sweep.
-    - cron: "0 4 * * 0"
+    # Weekly, after the Sunday s3-tests full sweep (starts 02:00 UTC, up to
+    # 3h) has finished, so the two never contend for the same runner pool.
+    - cron: "0 6 * * 0"
 
 env:
   S3_ACCESS_KEY: rustfsadmin