Add path filters to CI and build workflows

CI skips on changes to platform dirs (ios, linux, macos, web, windows),
docs, and README. Build skips on test-only changes since tests don't
affect the release APK.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.forgejo/workflows/ci.yml

@@ -2,7 +2,21 @@ name: CI
 
 on:
   push:
+    paths:
+      - "lib/**"
+      - "test/**"
+      - "pubspec.yaml"
+      - "pubspec.lock"
+      - "analysis_options.yaml"
+      - ".forgejo/workflows/ci.yml"
   pull_request:
+    paths:
+      - "lib/**"
+      - "test/**"
+      - "pubspec.yaml"
+      - "pubspec.lock"
+      - "analysis_options.yaml"
+      - ".forgejo/workflows/ci.yml"
 
 jobs:
   analyze: