feat: add cell name search to GET /api/cell/ endpoint

[aabhinavvvvvvv]

Fixes #527

Summary

Adds case-insensitive substring search for cells by name via the existing GET /api/cell/ endpoint.

Changes

• Cell.search_by_name(pattern) — new static method on the Cell model using SQLAlchemy ilike for case-insensitive matching (same pattern as Tag.search_by_name)
• GET /api/cell/?name=<query> — when name param is provided, returns cells whose names contain the given string (case-insensitive)
• Test — added test_cell_search_by_name covering full match, partial match, and no match cases

Usage

GET /api/cell/?name=station

[aleclevy]

@aabhinavvvvvvv I believe the test you made hangs indefinitely. Please test it and verify that it works as intended

[aabhinavvvvvvv]

@aabhinavvvvvvv I believe the test you made hangs indefinitely. Please test it and verify that it works as intended

Actually the test was using two different fixtures (setup_cells and init_database) in the same module that caused PostgreSQL lock conflict that hung indefinitely. I have fixed it here #695