init: extract mobile app from bincio_activity

Expo/React Native app with local SQLite archive and bincio-activity sync.

db/index.ts

@@ -0,0 +1,47 @@
+import type { SQLiteDatabase } from 'expo-sqlite';
+
+export async function migrateDb(db: SQLiteDatabase): Promise<void> {
+  await db.execAsync('PRAGMA journal_mode = WAL;');
+  await db.execAsync(`
+    CREATE TABLE IF NOT EXISTS activities (
+      id              TEXT PRIMARY KEY,
+      source_hash     TEXT NOT NULL,
+      detail_json     TEXT NOT NULL,
+      timeseries_json TEXT,
+      geojson         TEXT,
+      original_path   TEXT,
+      synced_at       INTEGER,
+      origin          TEXT NOT NULL CHECK(origin IN ('local', 'remote')),
+      created_at      INTEGER NOT NULL DEFAULT (unixepoch())
+    );
+
+    CREATE INDEX IF NOT EXISTS idx_activities_created_at
+      ON activities(created_at DESC);
+
+    CREATE TABLE IF NOT EXISTS settings (
+      key   TEXT PRIMARY KEY,
+      value TEXT NOT NULL
+    );
+  `);
+
+  // Migration v2: source_path stores the original filesystem path a file was
+  // imported from (e.g. /sdcard/Karoo/Rides/ride.fit), used for watch-folder
+  // deduplication without re-hashing files.
+  try {
+    await db.execAsync('ALTER TABLE activities ADD COLUMN source_path TEXT');
+    await db.execAsync(
+      'CREATE INDEX IF NOT EXISTS idx_activities_source_path ON activities(source_path)',
+    );
+  } catch {
+    // Column already exists — migration already ran, ignore.
+  }
+
+  // Migration v3: edits_json stores user overrides (e.g. {"title": "My title"})
+  // kept separate from detail_json so server re-extraction (Option A) never
+  // clobbers user edits.
+  try {
+    await db.execAsync('ALTER TABLE activities ADD COLUMN edits_json TEXT');
+  } catch {
+    // Column already exists — migration already ran, ignore.
+  }
+}