test(ime): run the native IBus E2E suite across four input engines

The native suite only ever exercised ibus-hangul, so every non-Korean IME
regression had to be caught by hand. Generalize the runner and spec over an
engine profile and add ibus-libpinyin (Pinyin), ibus-anthy (Romaji/kana) and
ibus-unikey (Telex) as matrix legs, covering the candidate-window, multi-commit
and rule-based rewriting shapes that Hangul alone does not produce.

Session config (apt package, GSettings, `ibus engine` name) and the keystroke
scripts live in separate files because one is loaded by the Node runner and the
other by the Playwright spec. They are joined only by the engine id, so the
contract test asserts the two sets agree and that the workflow matrix covers
exactly them.

Only the hangul expectations have been recorded from a real run. The other three
engines' committed glyphs are predicted from their input rules, so the exact-text
oracle is `expect.soft` for them while the structural oracle stays hard: every
repetition must produce identical bytes, in the engine's script, with xterm's
onData matching what the PTY received. That is the half that actually detects
the duplication and leaked-ASCII bugs, and it holds without knowing the glyphs.
A first green run turns each `expectationsVerified` to true.

fail-fast is off so a drifting libpinyin candidate cannot mask a hangul
regression, and evidence uploads are per-engine because upload-artifact rejects
a duplicate name.

.github/workflows/terminal-ime-e2e.yml

@@ -10,10 +10,26 @@ permissions:
 
 jobs:
   linux-x11:
-    name: Linux X11 terminal IME
+    name: Linux X11 terminal IME (${{ matrix.engine }})
     runs-on: ubuntu-22.04
     timeout-minutes: 25
 
+    strategy:
+      # Each engine is its own signal. A libpinyin candidate drifting must not
+      # hide a hangul regression, which is the one leg with recorded
+      # expectations.
+      fail-fast: false
+      matrix:
+        include:
+          - engine: hangul
+            apt-package: ibus-hangul
+          - engine: libpinyin
+            apt-package: ibus-libpinyin
+          - engine: anthy
+            apt-package: ibus-anthy
+          - engine: unikey
+            apt-package: ibus-unikey
+
     steps:
       - name: Checkout
         uses: actions/checkout@v6
@@ -28,7 +44,7 @@ jobs:
           dbus-x11
           dconf-gsettings-backend
           ibus
-          ibus-hangul
+          ${{ matrix.apt-package }}
           libglib2.0-bin
           python3
           xdotool
@@ -64,16 +80,16 @@ jobs:
           tests/e2e/terminal-ime-exact-byte.spec.ts
           --workers=1
 
-      - name: Run native IBus Hangul exact-byte tests
+      - name: Run native IBus ${{ matrix.engine }} exact-byte tests
         env:
           SKIP_BUILD: '1'
-        run: pnpm run test:e2e:terminal-ime-native
+        run: pnpm run test:e2e:terminal-ime-native -- --engine=${{ matrix.engine }}
 
       - name: Upload terminal IME evidence
         if: always()
         uses: actions/upload-artifact@v7
         with:
-          name: terminal-ime-evidence
+          name: terminal-ime-evidence-${{ matrix.engine }}
           path: test-results/
           retention-days: 7
           if-no-files-found: ignore