fix(storage): write synced news to local data path

[Iams4kura]

Summary

• Fixes: sync_from_remote reports a date as synchronized, but local date discovery and news queries cannot see the downloaded database.
• Root cause: The sync tool writes output//news.db while every local storage reader expects output/news/.db.

Regression evidence

• Before: uv run --frozen python -m unittest tests.test_storage_sync.StorageSyncTests.test_sync_downloads_news_database_to_readable_location -v exited 1

• After: uv run --frozen python -m unittest tests.test_storage_sync.StorageSyncTests.test_sync_downloads_news_database_to_readable_location -v exited 0

Verification

• PYTHONDONTWRITEBYTECODE=1 uv run --frozen python -m unittest discover -s tests -p 'test*.py' -v
• PYTHONDONTWRITEBYTECODE=1 uv sync --frozen --no-dev
• uv run --frozen python -m compileall trendradar mcp_server
• uv build

Scope

• 2 files changed, +58 / -3 lines