ci(web): replace wasm freshness gate with CI-side rebuild-and-commit

The rebuild-and-diff freshness gate (#93) could never pass: the Bevy wasm
artifacts aren't byte-reproducible across machines. Confirmed conclusively —
identical rustc 1.95.0 / LLVM 22.1.2, identical flags, Cargo.lock and remapped
source paths still yield host-dependent output (CI's build was 248 KB smaller
than a local one), while same-machine rebuilds are bit-identical. Path
remapping (kept in build_wasm.sh) is necessary but not sufficient.

Make CI the single source of truth instead: `web-wasm-rebuild` rebuilds pkg/ on
every master change to a wasm-feeding crate and commits it back. The deployed
artifacts can't silently rot and contributors no longer hand-run build_wasm.sh.
The pkg/ commit isn't in this workflow's trigger paths (no loop) but is in
docker-build's, so the refreshed wasm deploys.

Removes the false-failing web-wasm-freshness workflow.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.gitea/workflows/docker-build.yml

@@ -36,12 +36,12 @@ jobs:
         id: meta
         run: echo "sha=${GITHUB_SHA::8}" >> "$GITHUB_OUTPUT"
 
-      # WASM artifact freshness is enforced precisely by the dedicated
-      # `web-wasm-freshness` workflow (rebuild-and-diff on every PR + master
-      # push), which supersedes the previous changed-files heuristic here.
-      # That heuristic only hard-failed on direct solitaire_web/ edits and
-      # treated solitaire_engine/_core changes as a non-blocking notice, which
-      # let the whole card_game migration ship a stale pkg/.
+      # WASM artifact freshness is owned by the `web-wasm-rebuild` workflow,
+      # which rebuilds pkg/ in CI on every master change to a wasm-feeding crate
+      # and commits it back (CI is the single source of truth — the artifacts
+      # aren't byte-reproducible on contributor machines). That pkg/ commit then
+      # triggers this workflow, so the deployed image always ships fresh wasm.
+      # No drift check is needed here.
 
       - name: Log in to Gitea registry
         uses: docker/login-action@v3