ci: fix cache-key collisions and skip duplicate release-commit test run

The test job and build-linux shared one cargo cache key; the test job's
debug artifacts claimed it first and actions/cache skips saving on an
exact-key hit, so Linux release builds compiled cold every time (~31min
vs ~9min for the correctly-keyed Windows job). Same collision between
android-check and build-android. Give the release jobs their own keys.

Also skip build-and-test.yml for chore(release) commits: the tag push
triggers build-release.yml on the same commit, which runs the identical
test suite, and the two ~1h workflows contended for the single runner
slot.

.gitea/workflows/build-and-test.yml

@@ -16,6 +16,12 @@ on:
 jobs:
   test:
     name: Run Tests
+    # A release push triggers build-release.yml on the tag, which runs this exact
+    # test suite itself — and on a single-slot runner the two ~1h workflows would
+    # otherwise serialize/contend. Skip the duplicate for chore(release) commits.
+    # (head_commit is absent on pull_request/workflow_dispatch; startsWith(null,…)
+    # is false there, so those events still run.)
+    if: "!startsWith(github.event.head_commit.message, 'chore(release)')"
     runs-on: linux/amd64
     container:
       image: gitea.tourolle.paris/dtourolle/jellytau-builder:latest