fix(ci): job timeouts everywhere + retries on all network installs

Reliability pass over every workflow:
- timeout-minutes on all 21 jobs that lacked one (a hung job previously
  burned the 6-hour default runner budget)
- ./.github/actions/retry wrapped around every network-fetching install
  that lacked it: pip installs (deploy-site, skills-index), npm ci
  (deploy-site website, upload_to_pypi web + ui-tui), uv sync (docker
  test deps). Deterministic build steps (npm run build) deliberately
  NOT retried — split into separate steps so a real build failure fails
  fast instead of retrying 3x.

.github/workflows/ci.yml

@@ -35,6 +35,7 @@ jobs:
   detect:
     name: Detect affected areas
     runs-on: ubuntu-latest
+    timeout-minutes: 10
     outputs:
       python: ${{ steps.classify.outputs.python }}
       frontend: ${{ steps.classify.outputs.frontend }}
@@ -161,6 +162,7 @@ jobs:
       # - docker
     if: always()
     runs-on: ubuntu-latest
+    timeout-minutes: 10
     steps:
       - name: Evaluate job results
         env:
@@ -191,6 +193,7 @@ jobs:
     needs: [all-checks-pass, docker]
     if: always()
     runs-on: ubuntu-latest
+    timeout-minutes: 10
     steps:
       - name: Checkout code
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2