Implement Phase 1 Android client: Flutter share receiver + upload service

- Register ACTION_SEND IntentFilter for image/* in AndroidManifest
- Kotlin MethodChannel bridge: extract image URI, original filename, resolve to file
- Flutter bottom sheet UI: thumbnail preview, note input (200 char), submit/cancel
- Upload service: multipart POST, Bearer auth, 10MB limit, offline cache, exponential backoff retry
- Configurable server URL and API token via SharedPreferences
- Minimal home screen with usage instructions

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

windows/runner/resource.h

@@ -0,0 +1,16 @@
+//{{NO_DEPENDENCIES}}
+// Microsoft Visual C++ generated include file.
+// Used by Runner.rc
+//
+#define IDI_APP_ICON                    101
+
+// Next default values for new objects
+//
+#ifdef APSTUDIO_INVOKED
+#ifndef APSTUDIO_READONLY_SYMBOLS
+#define _APS_NEXT_RESOURCE_VALUE        102
+#define _APS_NEXT_COMMAND_VALUE         40001
+#define _APS_NEXT_CONTROL_VALUE         1001
+#define _APS_NEXT_SYMED_VALUE           101
+#endif
+#endif