app: .fingerprintignore .gitignore + stop biome reformatting Icon Composer bundles

The v0.0.2-era OTA never reached TestFlight because the fingerprint
runtime drifted on three non-native edits. Each gets its own treatment:

- .gitignore → .fingerprintignore: only affects file collection, zero
  native-build effect
- assets/sidecode.icon: NOT fingerprint-ignored (real icon changes must
  flip the runtime) — instead biome stops reformatting Icon Composer's
  generated icon.json, whose whitespace churn is what flipped the hash
- package.json scripts: deliberately left fingerprinted (eas-build-*
  hooks live there)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: yyq1025

biome.json

@@ -7,7 +7,12 @@
   },
   "files": {
     "ignoreUnknown": false,
-    "includes": ["**", "!**/*.astro", "!packages/app/src/uniwind-types.d.ts"]
+    "includes": [
+      "**",
+      "!**/*.astro",
+      "!packages/app/src/uniwind-types.d.ts",
+      "!packages/app/assets/**/*.icon"
+    ]
   },
   "formatter": {
     "enabled": true,

packages/app/.fingerprintignore

@@ -0,0 +1,11 @@
+# Paths @expo/fingerprint should NOT hash into the runtime version.
+# Keep this list minimal — every entry trades OTA-vs-native safety for
+# less fingerprint churn. Things that look like noise but MUST stay
+# fingerprinted: package.json scripts (eas-build-* hooks live there),
+# patches/, and every config-referenced asset (icon/splash compile into
+# the native binary).
+#
+# .gitignore only affects which files get collected — it has zero effect
+# on the native build, but hashing it flipped the fingerprint when an
+# unrelated ignore rule changed (the v0.0.2-era TestFlight OTA miss).
+.gitignore