Initial Full Scan pipeline

[c5ln]

Summary:

Walk all .py files in a repository, run extraction (Issue #2, #3) per file, and batch INSERT into SQLite within a single transaction.

Tasks:

• Recursive directory traversal (filter .py files)
• Prepared statement creation for all 6 tables
• Batch INSERT within BEGIN/COMMIT transaction
• sqlite3_bind_* parameter binding (no string concatenation)
• Full Rescan mode: DELETE FROM file before INSERT (cascade clears all)