test: audit suite for meaningfulness, reach 100% coverage

The suite had 8 empty `pass` tests, two tests that made live network
calls to a production healthcheck endpoint, and a write_csv test that
only asserted the file existed. CI ran only test_komodo_deploy, so the
main suite never executed at all.

- Split tests by module: test_qlist, test_qprocess, test_qlogging_extra,
  test_apprise, test_qbt; rewrote test_qbitmaid and test_write_csv.
- qbt_fakes.py: shared fakes (FakeQbt, FakeQbtClient, FakeAPIError,
  StubPushover, FailingPushover, torrent factory).
- test_qbt.py loads the hyphenated qbit-maid.py via importlib and covers
  the __main__ entry point.
- Replaced the live-network tests with a RecordingRequests stub
  (suite time 14s -> 0.035s).
- .coveragerc + CI unit-tests job running the full suite with
  --fail-under=100.

127 unit tests, 100% statement coverage on all 5 first-party modules
(440 stmts), 15/15 mutations caught.

Seven pre-existing bugs are pinned by tests with KNOWN BUG docstrings
and left unfixed pending a decision.

.gitea/workflows/test.yml

@@ -8,6 +8,24 @@ on:
   pull_request:
 
 jobs:
+  unit-tests:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Install dependencies
+        # Mirrors the Dockerfile: the container installs qbittorrent-api
+        # unpinned, so requirements.txt is not used here.
+        run: |
+          python3 -m pip install --upgrade pip
+          python3 -m pip install requests qbittorrent-api coverage
+      - name: Run the full suite with coverage
+        run: |
+          python3 -m coverage run --rcfile=.coveragerc -m unittest \
+            test_qbitmaid test_write_csv test_qlist test_qprocess \
+            test_qlogging_extra test_apprise test_qbt
+          python3 -m coverage report -m --fail-under=100
+
   komodo-deploy-script:
     runs-on: ubuntu-latest
     steps: