Ci run all dart tests (#16328)

* ci: run every Dart test, not three files

The step ran only the three cursor test files, so the other nine files
under flutter/test (terminal, file model, autocomplete, ...) never ran
on any pull request. With no path the runner takes the whole directory.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EZ49AbZJYfm8NTp5yDPMab

* ci: run the Rust tests CI could not reach

cargo test --workspace runs with the default features on x86_64 Linux
only, so the tests behind `windows`, `not(target_os = "linux")`,
`unix-file-copy-paste` and drmtap_dl's `tests` module never ran: the
platform, portable-service and audio tests, the clipboard crate's file
copy-paste and Windows file-name tests, and the drmtap loader's.

The macOS and Windows build jobs now run `cargo test --lib` after the
build with the build's own feature set, plus the clipboard crate. The
Linux job's list of named test runs gains drmtap_dl and the clipboard
feature. AGENTS.md says where tests go and what CI runs.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EZ49AbZJYfm8NTp5yDPMab
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WS1HTjp6UQuG43KEcQPq1R

* ci: drop the skips for tests that no longer exist

#16539 removed test_get_cursor_pos and test_get_key_state, the only
tests these skips matched.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WS1HTjp6UQuG43KEcQPq1R

---------

Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>

.github/workflows/flutter-build.yml

@@ -366,6 +366,17 @@ jobs:
               Write-Host "Ingore the printer driver error."
           }
 
+      - name: Run the Rust tests
+        # x86_64 only: the tests are the same code on arm64, and that runner is the slow one.
+        if: ${{ !inputs.upload-artifact && matrix.job.arch == 'x86_64' }}
+        shell: bash
+        run: |
+          # The build's own features, so the tests see the code that ships.
+          FEATURES=$(python3 ./build.py --portable --flutter --skip-portable-pack --hwcodec ${{ matrix.job.build-args }} --print-features)
+          cargo test --locked --release --lib --features "$FEATURES"
+          # Its Windows tests run nowhere else.
+          cargo test --locked --release -p clipboard
+
       - name: find Runner.res
         # Windows: find Runner.res (compiled from ./flutter/windows/runner/Runner.rc), copy to ./Runner.res
         # Runner.rc does not contain actual version, but Runner.res does
@@ -965,10 +976,10 @@ jobs:
           name: bridge-artifact
           path: ./
 
-      - name: Test cursor sizing
+      - name: Run the Dart tests
         if: ${{ !inputs.upload-artifact && matrix.job.arch == 'aarch64' }}
         working-directory: flutter
-        run: flutter test --timeout 60s test/cursor_size_test.dart test/cursor_replay_test.dart test/cursor_default_test.dart
+        run: flutter test --timeout 60s
 
       - name: Setup vcpkg with Github Actions binary cache
         uses: lukka/run-vcpkg@b1a0dd252f06b9e25b3c022a9a03bd7a427fb6a2 # v11
@@ -1022,6 +1033,16 @@ jobs:
           cargo test --locked --release --lib verified_dmg_tests --features "flutter,hwcodec,unix-file-copy-paste${{ matrix.job.extra-cargo-features }}"
           cargo test --locked --release --lib update_metadata::tests --features "flutter,hwcodec,unix-file-copy-paste${{ matrix.job.extra-cargo-features }}"
 
+      - name: Run the Rust tests
+        if: ${{ !inputs.upload-artifact && matrix.job.arch == 'aarch64' }}
+        run: |
+          # The build's own features, so the tests see the code that ships. MACOSX_DEPLOYMENT_TARGET
+          # comes from the build step's export.
+          FEATURES=$(./build.py --flutter --hwcodec --unix-file-copy-paste ${{ matrix.job.extra-build-args }} --print-features)
+          cargo test --locked --release --lib --features "$FEATURES"
+          # Opt-in, and its macOS tests run nowhere else.
+          cargo test --locked --release -p clipboard --features unix-file-copy-paste
+
       - name: create unsigned dmg
         if: env.UPLOAD_ARTIFACT == 'true'
         run: |
@@ -2354,6 +2375,11 @@ jobs:
               cargo test --locked -p scrap --features drm crtc_refresh_tests
             run_drm_tests "scrap plane_rotation_tests" \
               cargo test --locked -p scrap --features drm plane_rotation_tests
+            run_drm_tests "scrap drmtap_dl::tests" \
+              cargo test --locked -p scrap --features drm drmtap_dl::tests
+            # Opt-in like drm, and this container already builds with it.
+            run_drm_tests "clipboard unix-file-copy-paste" \
+              cargo test --locked -p clipboard --features unix-file-copy-paste
             cargo build --locked --lib --features "$FEATURES" --release
             rm -rf target/release/deps target/release/build
             rm -rf ~/.cargo