fix(ci): resolve 27 hypatia workflow-hygiene findings

[hyperpolymath]

Summary

Triggered by the hypatia scan comment on PR #249 — 98 findings flagged. This PR resolves 27 of them at root cause; another ~9 `CSA001` mirrors will clear automatically when the source findings clear.

Findings resolved

Count	Severity	Type	Fix
1	medium	`unpinned_action`	`governance.yml` `@main` → SHA pin matching estate convention
23	medium	`missing_timeout_minutes`	Every job + reusable-workflow caller gets explicit `timeout-minutes` (10–60 min, scaled to job nature)
1	medium	`codeql_missing_actions_language`	Drop `javascript-typescript` (not in repo), add `actions` to matrix
1	medium	`StaticAnalysis`	Same as above (different presentation)
1	high	`scorecard_publish_with_run_step`	Split `scorecard-enforcer.yml` into action-only `scorecard` job + downstream `score-gate` job consuming SARIF via artifact
1	high	`secret_action_without_presence_gate`	Gate `instant-sync.yml`'s `FARM_DISPATCH_TOKEN` with `env.HAS_TOKEN` check; add skip-notice step for token-absent path

Out of scope (separate work)

Count	Severity	Type	Why deferred
6	critical	`SD004`	Hypatia rule bug — enforcing retired `.machine_readable/6a2/` subdir layout. Per standards CLAUDE.md, canonical location IS `.machine_readable/` directly. File hypatia issue.
29	medium	`expect_in_hot_path`	Rust `.expect()` calls across `bots/*`. Needs per-bot review + migration to `?` / `unwrap_or_else`. Separate code work.
1	medium	`GS007`	3 stale non-main remote branches. Cleanup separately.
33+1	medium	`CSA001`/`CSA002`	Code-scanning-API mirrors of other findings. Resolve automatically when sources resolve.

Key design notes

Scorecard split

Hypatia's `scorecard_publish_with_run_step` rule flags any `run:` step in a workflow job using `ossf/scorecard-action` with `publish_results: true`. The OpenSSF publish protocol expects the action to be the only thing in the job. Restructured:

scorecard:        # action-only: checkout → run scorecard → upload SARIF → upload artifact
score-gate:       # needs: scorecard. Pulls artifact, runs score check via run-step
check-critical:   # existing, unchanged

Secret presence gate

The canonical `if: env.HAS_TOKEN == 'true'` pattern guards the dispatch step. Adds explicit skip-notice for forks / PRs from forks where the token is absent — better UX than opaque 401s.

Reusable-workflow callers

GitHub allows `timeout-minutes` on `uses:` caller jobs (caps total reusable execution time). Used on the 5 reusable wrappers: governance / hypatia-scan / mirror / scorecard / secret-scanner.

Test plan

• Hypatia scan on this PR drops from 98 → ~38 findings (no critical/high in workflow surface).
• All workflows still run cleanly (timeout caps are generous — 30+ min for any non-trivial scan).
• `scorecard-enforcer.yml` still produces a score-gate failure on regression (verified by reading; will need CI run to confirm).

Related

• feat(scripts): propagate-sha-bump.sh — actuation for hypatia#418 (#248) #249 — the actuation PR whose scan comment surfaced these findings.
• hyperpolymath/hypatia — SD004 rule needs fixing separately (will file).

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