Whole-project `flutter analyze` exited 1 on 17 pre-existing info/warning
lints (no errors) in dev tools and test files. Clean them so analyze is
green:
- editor_repository_test: drop the redundant sqflite_common import; keep
the used utils import with a transitive-dep ignore.
- pen_* widget tests: `(_, __)` wildcard params -> `(_, _)`.
- search_snippet_test / gen_bench_pdf / gen_dense_strokes: drop needless
interpolation braces; remove an unused `Size` show and an unused local;
mark the gen tool as print-allowed.
No runtime behavior changed. flutter analyze: No issues found. Affected
tests: 22/22 pass.
Add pdfrx 2.4.4. PenCaptureRegion routes stylus to ink (arena-bypass
via PenCaptureBinding) while touch falls through to pdfrx scroll/zoom.
Spike pane hosts PdfViewer with page-overlay ink at normalized coords +
frame-time HUD; reachable from home screen for on-device testing.
Bench/coordinate harness under integration_test. Generated assets are
gitignored (regenerate via tool/gen_*.dart).
