CI: cherry-pick shell:bash + OS-split test filename convention from PR 820 (#12)

* CI: add shell: bash to unit-test-linux + integration-test steps

Root cause of "Unit Tests (Linux)" and "Integration Tests (Gramps)"
failures was not broken test modules — the steps never invoked
unittest. The container's default shell is /bin/sh (dash on
python:3.12-slim), and the inline scripts use bash-only parameter
expansions (${f%.py}, ${mod//\//.}) to build the dotted module list.
Dash fails with "Bad substitution" on the first such line; the rest
of the script never runs. continue-on-error: true masked this as a
generic job failure for two CI rounds.

Add "shell: bash" explicitly to:
- unit-test-linux / Run per-addon unit tests (bashisms)
- integration-test / Run per-addon integration tests (bashisms)
- integration-test / Run plugin registration tests (no bashisms today,
  but consistent and future-proof)

Compile Check already sets shell: bash. Windows jobs inherit bash
via defaults.run at the job level. No other steps affected.

* CI: split OS-specific addon tests via filename convention

The Windows unit-test job hung on TMGimporter's DB-backed tests because
make_database("sqlite").load(":memory:", None) deadlocks under the
conda-forge GTK + pip Gramps combination. Rather than patch the hang,
introduce a filename convention so per-addon authors can declare OS
scope up front:

  test_*.py              general (every OS)
  test_linux_*.py        Linux-only
  test_windows_*.py      Windows-only
  test_integration_*.py  Linux-only, full-pipeline/DB-backed (pre-existing)

unit-test-linux skips test_windows_* and test_integration_*;
unit-test-windows skips test_linux_* and test_integration_*.

Applied to TMGimporter: the 13 DB-backed classes in tests/test_libtmg.py
move to tests/test_linux_libtmg.py (along with the _Rec/_table/_make_db/
_add_person/_MockUser helpers they use). The 7 pure-logic classes
(TestStripTmgCodes, TestTmgDateToGrampsDate, TestNumTo{Month,Date},
TestParseDate, TestRepoTypeFromName, TestUrlFromName) stay in
test_libtmg.py and will run on every OS.

Locally all 175 tests still pass via run-addon-unit.sh TMGimporter.

Author: eduralph

.github/workflows/ci.yml

@@ -101,6 +101,19 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: Run per-addon unit tests
+        # Filename convention (all OSes):
+        #   test_*.py              — general (any OS)
+        #   test_linux_*.py        — Linux-only
+        #   test_windows_*.py      — Windows-only
+        #   test_integration_*.py  — Linux-only, full-pipeline/DB-backed
+        # The Linux job runs test_*.py except the Windows-only and
+        # integration buckets. Integration tests run in their own job.
+        #
+        # shell: bash — the container's default shell is /bin/sh
+        # (dash on python:3.12-slim), which does not support the
+        # ${var//pattern/repl} and ${var%.py} parameter expansions
+        # used below. Falls silently under continue-on-error.
+        shell: bash
         env:
           PYTHONPATH: .
         run: |
@@ -109,6 +122,7 @@ jobs:
             [ -f "$f" ] || continue
             case "$(basename "$f")" in
               test_integration*) continue ;;
+              test_windows_*)    continue ;;
             esac
             case "$f" in
               Sqlite/tests/test_sqlite.py) continue ;;
@@ -153,6 +167,8 @@ jobs:
           python -c "import gramps, gi; print('deps OK')"
 
       - name: Run per-addon unit tests
+        # See filename-convention note in unit-test-linux. The Windows
+        # job runs test_*.py except test_linux_* and test_integration_*.
         env:
           PYTHONPATH: .
         run: |
@@ -161,6 +177,7 @@ jobs:
             [ -f "$f" ] || continue
             case "$(basename "$f")" in
               test_integration*) continue ;;
+              test_linux_*)      continue ;;
             esac
             case "$f" in
               Sqlite/tests/test_sqlite.py) continue ;;
@@ -190,11 +207,19 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: Run plugin registration tests
+        # shell: bash for consistency with the surrounding steps; the
+        # current command uses no bashisms, but keeps this block safe
+        # against future edits. Container default is /bin/sh → dash.
+        shell: bash
         env:
           PYTHONPATH: .
         run: python3 -m unittest discover -s tests -p "test_*.py" -t . -v
 
       - name: Run per-addon integration tests
+        # shell: bash — see unit-test-linux for rationale; the
+        # ${var//pattern/repl} and ${var%.py} expansions below are
+        # bash-only.
+        shell: bash
         env:
           PYTHONPATH: .
         run: |