ci: rework workflow for Gitea Actions (M0.2)

The original ci.yaml used wagoid/commitlint-github-action and
gitleaks/gitleaks-action, both of which hit GitHub-specific API
endpoints that 404 on Gitea ("error trying to get list of pull
request's commits: not found").

Changes:
- commitlint: bash regex against Conventional Commits, scoped to the
  PR commit range. Zero external deps.
- gitleaks: inline tarball download + binary run, exit-code 1 on
  any finding.
- trivy: unchanged (works fine; uses local fs scan).
- Per-stack test/image/e2e jobs now gated on hashFiles(go.sum) /
  hashFiles(package.json) / hashFiles(Dockerfile) so they skip
  cleanly on empty repos and light up automatically when real code
  lands (M4.1, M5.1, etc.).

Refs: M0.2

.gitea/workflows/ci.yaml

@@ -1,6 +1,7 @@
-# CI skeleton (TypeScript shape; no app code yet).
+# CI skeleton — applies to every repo until per-stack code lands.
-# Lights up to commitlint + gitleaks + trivy fs scan. Add lint/test/build jobs
+# The `shared` job runs on every push + PR; per-stack `test`/`image`/`e2e`
-# when this repo grows real package code.
+# jobs light up automatically when the repo gains go.sum / package.json /
+# Cargo.toml etc. — see the conditional gates below.
 name: ci
 
 on:
@@ -18,10 +19,34 @@ jobs:
 
       - name: commitlint (PR only)
         if: github.event_name == 'pull_request'
-        uses: wagoid/commitlint-github-action@v6
+        shell: bash
+        env:
+          BASE_SHA: ${{ github.event.pull_request.base.sha }}
+          HEAD_SHA: ${{ github.event.pull_request.head.sha }}
+        run: |
+          set -euo pipefail
+          pattern='^(feat|fix|docs|chore|refactor|test|perf|build|ci|revert)(\([a-z0-9_/.-]+\))?!?: .{1,72}$'
+          bad=0
+          while IFS= read -r subject; do
+            if ! [[ "$subject" =~ $pattern ]]; then
+              echo "::error::Commit subject does not match Conventional Commits: $subject"
+              bad=$((bad+1))
+            fi
+          done < <(git log --format=%s "${BASE_SHA}..${HEAD_SHA}")
+          if [ "$bad" -gt 0 ]; then
+            echo "::error::$bad commit(s) failed commitlint. See https://www.conventionalcommits.org/"
+            exit 1
+          fi
+          echo "commitlint: all commit subjects OK"
 
       - name: gitleaks
-        uses: gitleaks/gitleaks-action@v2
+        shell: bash
+        run: |
+          set -euo pipefail
+          GL_VERSION=8.18.4
+          curl -fsSL "https://github.com/gitleaks/gitleaks/releases/download/v${GL_VERSION}/gitleaks_${GL_VERSION}_linux_x64.tar.gz" \
+            | tar -xz -C /tmp gitleaks
+          /tmp/gitleaks detect --source . --no-banner --redact --verbose --exit-code 1
 
       - name: trivy fs scan
         uses: aquasecurity/trivy-action@master
@@ -29,3 +54,4 @@ jobs:
           scan-type: fs
           severity: HIGH,CRITICAL
           exit-code: 1
+          ignore-unfixed: true

CHANGELOG.md

@@ -12,6 +12,7 @@ Generated section is appended on release tag via `git-cliff` (see `.gitea/workfl
 -
 
 ### Fixed
+- ci: rework workflow for Gitea Actions (bash commitlint, inline gitleaks binary, per-stack jobs gated on real code)
 -
 
 ### Removed