feat(editor): M1 pdfrx spike + pen/touch capture

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).

pubspec.lock

@@ -25,6 +25,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.13.4"
+  archive:
+    dependency: transitive
+    description:
+      name: archive
+      sha256: a96e8b390886ee8abb49b7bd3ac8df6f451c621619f52a26e815fdcf568959ff
+      url: "https://pub.dev"
+    source: hosted
+    version: "4.0.9"
   args:
     dependency: transitive
     description:
@@ -318,6 +326,11 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.1.0"
+  flutter_driver:
+    dependency: transitive
+    description: flutter
+    source: sdk
+    version: "0.0.0"
   flutter_lints:
     dependency: "direct dev"
     description:
@@ -384,6 +397,11 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "4.0.0"
+  fuchsia_remote_debug_protocol:
+    dependency: transitive
+    description: flutter
+    source: sdk
+    version: "0.0.0"
   glob:
     dependency: transitive
     description:
@@ -440,6 +458,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "4.1.2"
+  image:
+    dependency: transitive
+    description:
+      name: image
+      sha256: f9881ff4998044947ec38d098bc7c8316ae1186fa786eddffdb867b9bc94dfce
+      url: "https://pub.dev"
+    source: hosted
+    version: "4.8.0"
   image_picker:
     dependency: "direct main"
     description:
@@ -504,6 +530,11 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.2.2"
+  integration_test:
+    dependency: "direct dev"
+    description: flutter
+    source: sdk
+    version: "0.0.0"
   intl:
     dependency: transitive
     description:
@@ -712,6 +743,38 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.3.0"
+  pdfium_dart:
+    dependency: transitive
+    description:
+      name: pdfium_dart
+      sha256: "86e95c66b09f3245b95c4924f2edce8d4f7c9786876e5c5ee8e36b104a94bbb0"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.2.5"
+  pdfium_flutter:
+    dependency: transitive
+    description:
+      name: pdfium_flutter
+      sha256: "420ba8e7673b54da387ceeeb18a72c8bc6e4452128dbb391dca900c748f9e9ba"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.2.2"
+  pdfrx:
+    dependency: "direct main"
+    description:
+      name: pdfrx
+      sha256: e0ca318004c3f32144db8e74fa612abb80ebe79004677293af74ed9af119f47f
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.4.4"
+  pdfrx_engine:
+    dependency: transitive
+    description:
+      name: pdfrx_engine
+      sha256: "89865e158ced818690ab207a13a34a65803cd67ee1bec9f5f87838eb5a79600b"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.4.3"
   perfect_freehand:
     dependency: "direct main"
     description:
@@ -752,6 +815,22 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.5.2"
+  posix:
+    dependency: transitive
+    description:
+      name: posix
+      sha256: "185ef7606574f789b40f289c233efa52e96dead518aed988e040a10737febb07"
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.5.0"
+  process:
+    dependency: transitive
+    description:
+      name: process
+      sha256: c6248e4526673988586e8c00bb22a49210c258dc91df5227d5da9748ecf79744
+      url: "https://pub.dev"
+    source: hosted
+    version: "5.0.5"
   pub_semver:
     dependency: transitive
     description:
@@ -808,6 +887,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.6.4"
+  rxdart:
+    dependency: transitive
+    description:
+      name: rxdart
+      sha256: "5c3004a4a8dbb94bd4bf5412a4def4acdaa12e12f269737a5751369e12d1a962"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.28.0"
   shared_preferences:
     dependency: "direct main"
     description:
@@ -1005,6 +1092,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.4.1"
+  sync_http:
+    dependency: transitive
+    description:
+      name: sync_http
+      sha256: "7f0cd72eca000d2e026bcd6f990b81d0ca06022ef4e32fb257b30d3d1014a961"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.3.1"
   syncfusion_flutter_core:
     dependency: transitive
     description:
@@ -1229,6 +1324,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "3.0.3"
+  webdriver:
+    dependency: transitive
+    description:
+      name: webdriver
+      sha256: "2f3a14ca026957870cfd9c635b83507e0e51d8091568e90129fbf805aba7cade"
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.1.0"
   win32:
     dependency: transitive
     description:
@@ -1271,4 +1374,4 @@ packages:
     version: "3.1.3"
 sdks:
   dart: ">=3.10.8 <4.0.0"
-  flutter: ">=3.38.4"
+  flutter: ">=3.41.0"