test: cover IME InputConnection integration

[zefutoff]

Add end-to-end Android instrumentation coverage for the Grammalecte IME.

The test:

• waits for Android to register the packaged IME;
• enables and selects the Grammalecte IME through the Android framework;
• launches a real editable EditText;
• exposes selected text through a real InputConnection;
• performs a real Grammalecte correction;
• verifies that corrected text is committed back into the editor;
• restores the previous input method afterward.

Also updates the roadmap, testing documentation and changelog.

Validated locally with:

• make check
• make assemble
• full :app:connectedDebugAndroidTest
• Samsung Galaxy S21 / Android 15