Re-apply deploy.yml pinning behind a deploy guard, and probe the failure

Restores the hash-pinning work reverted in 3d17e22 (originally 3f91a7c and
b157bfd) verbatim -- all six pinned values were independently re-resolved and
confirmed correct twice, so they are reused, not re-derived.

What is different this time is that the path is observable before it reaches
main. The previous attempt broke the deploy because deploy.yml triggers only on
push to main, so every pre-merge check simulated the runner instead of being
it, and two adversarial reviews could not catch what neither could execute.

Three changes on top of the restored work:

- A temporary development-only branch trigger on on.push.branches, so the
  build job actually executes under act_runner. Removed before merge.
- if: github.ref_name == 'main' on the deploy job. Without it, a branch push
  would run wrangler pages deploy against the real Cloudflare project with the
  real token on every iteration. This guard is permanent: it is one line and it
  makes any future branch trigger, deliberate or accidental, unable to reach
  Cloudflare.
- A temporary .gitea/workflows/probe.yml, also deleted before merge. The
  Actions jobs and logs API is not readable by this account; the commit-status
  API is, and it reports one entry per job. So the diagnosis is encoded as job
  topology rather than log output: six jobs, each isolating one hypothesis
  about the 22s failure (bare alpine vs apk prerequisites, checkout vs site
  build vs artifact upload, musl node vs glibc node), each surfacing as its own
  status context so a single push tests them all in parallel.

make check is green. No pinned value is touched.

.gitea/workflows/probe.yml

@@ -0,0 +1,110 @@
+# TEMPORARY diagnostic workflow. Deleted before this branch is merged.
+#
+# The Actions jobs/logs API is not readable by this account, so the only
+# available signal is the commit-status API, which reports one entry per
+# *job*. This file therefore encodes the diagnosis as job topology: each job
+# below isolates exactly one hypothesis about why the pinned-alpine build job
+# failed after 22s on main (run 25), and each shows up as its own status
+# context, so one push tests them all in parallel.
+name: probe
+
+on:
+    push:
+        branches:
+            - pin-deploy-refs-observable
+
+jobs:
+    # Control. If this passes, act_runner supplies its own node for JS actions
+    # and the whole "install node first" theory is wrong.
+    p1-bare-alpine-checkout:
+        runs-on: ubuntu-latest
+        container:
+            # alpine 3.21, 2026-02-28
+            image: alpine@sha256:c3f8e73fdb79deaebaa2037150150191b9dcbfba68b4a46d70103204c53f4709
+        steps:
+            # actions/checkout v4.2.2, 2026-02-28
+            - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+
+    # Exactly the reverted prefix: apk prerequisites, then checkout. Isolates
+    # checkout from everything downstream of it.
+    p2-alpine-apk-checkout:
+        runs-on: ubuntu-latest
+        container:
+            # alpine 3.21, 2026-02-28
+            image: alpine@sha256:c3f8e73fdb79deaebaa2037150150191b9dcbfba68b4a46d70103204c53f4709
+        defaults:
+            run:
+                shell: sh
+        steps:
+            - run: apk add --no-cache nodejs git tar
+            # actions/checkout v4.2.2, 2026-02-28
+            - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+              with:
+                  submodules: recursive
+
+    # p2 plus the site build. Isolates script/bootstrap and script/test inside
+    # the Actions container from the JS-action machinery.
+    p3-alpine-apk-build:
+        runs-on: ubuntu-latest
+        container:
+            # alpine 3.21, 2026-02-28
+            image: alpine@sha256:c3f8e73fdb79deaebaa2037150150191b9dcbfba68b4a46d70103204c53f4709
+        defaults:
+            run:
+                shell: sh
+        steps:
+            - run: apk add --no-cache nodejs git tar
+            # actions/checkout v4.2.2, 2026-02-28
+            - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+              with:
+                  submodules: recursive
+            - run: script/bootstrap
+            - run: script/test
+            - run: tar -czf site.tar.gz public
+
+    # p2 plus the artifact upload. This is the one step whose protocol changed
+    # in this issue (v3 -> v4) and the ~22s timing is consistent with reaching
+    # it.
+    p4-alpine-apk-upload:
+        runs-on: ubuntu-latest
+        container:
+            # alpine 3.21, 2026-02-28
+            image: alpine@sha256:c3f8e73fdb79deaebaa2037150150191b9dcbfba68b4a46d70103204c53f4709
+        defaults:
+            run:
+                shell: sh
+        steps:
+            - run: apk add --no-cache nodejs git tar
+            # actions/checkout v4.2.2, 2026-02-28
+            - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+            - run: tar -czf probe4.tar.gz hugo.toml
+            # actions/upload-artifact v4.6.2, 2026-08-09
+            - uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02
+              with:
+                  name: probe4
+                  path: probe4.tar.gz
+
+    # Fallback image direction, measured rather than assumed: an image that
+    # already carries node.
+    p5-node20alpine-checkout:
+        runs-on: ubuntu-latest
+        container:
+            # node 20-alpine, 2026-08-09
+            image: node@sha256:fb4cd12c85ee03686f6af5362a0b0d56d50c58a04632e6c0fb8363f609372293
+        defaults:
+            run:
+                shell: sh
+        steps:
+            # actions/checkout v4.2.2, 2026-02-28
+            - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+
+    # The glibc control. If musl node is the problem, this passes where the
+    # alpine jobs do not.
+    p6-node20slim-checkout:
+        runs-on: ubuntu-latest
+        container:
+            # node 20-bookworm-slim, 2026-08-09
+            image: node@sha256:2cf067cfed83d5ea958367df9f966191a942351a2df77d6f0193e162b5febfc0
+        steps:
+            # actions/checkout v4.2.2, 2026-02-28
+            - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683