feat: add nowcast point alarm page client with SQLite store

Adds point_alarm.py (flattening, secret masking, SQLite upsert store, paged fetch with 403 fallback, CSV/TXT export, shared filter loader), nowcast-point-page.py CLI and unit tests. Register will read the shared filter from nowcast-point-alarm-filter.json instead of repeating it in the CSV.

nowcast_common.py

@@ -12,7 +12,7 @@ from typing import Any
 from urllib.parse import urlsplit
 from uuid import UUID
 
-from common import ConfigurationError
+from common import ApiError, ConfigurationError, IklimClient
 
 
 AUTHENTICATION_FIELDS = {
@@ -154,3 +154,14 @@ def write_csv_atomic(
     finally:
         if temp_path and temp_path.exists():
             temp_path.unlink()
+
+
+def fetch_account_id(client: IklimClient) -> str:
+    """Return the caller's account id from /v1/users/me."""
+    response = client.request_json("GET", "/v1/users/me")
+    data = response.data
+    account = data.get("account") if isinstance(data, dict) else None
+    account_id = account.get("id") if isinstance(account, dict) else None
+    if not as_uuid(account_id):
+        raise ApiError("/v1/users/me yanıtında geçerli account.id bulunamadı.")
+    return account_id