implement server mvp: fastapi app, org formatter, sqlite store, tests, dockerfile

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

server/app/store.py

@@ -0,0 +1,38 @@
+import sqlite3
+import threading
+from pathlib import Path
+
+
+_lock = threading.Lock()
+
+
+def _connect(db_path: str) -> sqlite3.Connection:
+    conn = sqlite3.connect(db_path, check_same_thread=False)
+    conn.execute(
+        "CREATE TABLE IF NOT EXISTS seen_ids (id TEXT PRIMARY KEY, created_at TEXT NOT NULL)"
+    )
+    conn.commit()
+    return conn
+
+
+class IdempotencyStore:
+    def __init__(self, db_path: str) -> None:
+        Path(db_path).parent.mkdir(parents=True, exist_ok=True)
+        self._conn = _connect(db_path)
+
+    def already_seen(self, capture_id: str) -> bool:
+        row = self._conn.execute(
+            "SELECT 1 FROM seen_ids WHERE id = ?", (capture_id,)
+        ).fetchone()
+        return row is not None
+
+    def mark_seen(self, capture_id: str, created_at: str) -> None:
+        self._conn.execute(
+            "INSERT OR IGNORE INTO seen_ids (id, created_at) VALUES (?, ?)",
+            (capture_id, created_at),
+        )
+        self._conn.commit()
+
+
+def get_file_lock() -> threading.Lock:
+    return _lock