Unify attachment display and enable file uploads on all platforms (#1501)

Attachment pills were drawn by four separate style sets, so files,
images, GitHub items, and reviews rendered at different heights in the
same tray. Move the frame, the two-line label, and the image thumbnail
into shared components so every attachment lines up at one height,
across both the composer and sent messages.

Sent-message images now open the lightbox, and file uploads work on
iOS and Android via expo-document-picker instead of being gated to
desktop.

package-lock.json

@@ -20410,6 +20410,15 @@
         "expo": "*"
       }
     },
+    "node_modules/expo-document-picker": {
+      "version": "14.0.8",
+      "resolved": "https://registry.npmjs.org/expo-document-picker/-/expo-document-picker-14.0.8.tgz",
+      "integrity": "sha512-3tyQKpPqWWFlI8p9RiMX1+T1Zge5mEKeBuXWp1h8PEItFMUDSiOJbQ112sfdC6Hxt8wSxreV9bCRl/NgBdt+fA==",
+      "license": "MIT",
+      "peerDependencies": {
+        "expo": "*"
+      }
+    },
     "node_modules/expo-eas-client": {
       "version": "1.0.8",
       "resolved": "https://registry.npmjs.org/expo-eas-client/-/expo-eas-client-1.0.8.tgz",
@@ -37111,6 +37120,7 @@
         "expo-constants": "~18.0.9",
         "expo-crypto": "^15.0.8",
         "expo-dev-client": "^6.0.15",
+        "expo-document-picker": "~14.0.8",
         "expo-file-system": "~19.0.17",
         "expo-haptics": "~15.0.7",
         "expo-image": "~3.0.10",