Fix: Stop tracking ChromaDB SQLite files to prevent merge conflicts

[sharma-sugurthi]

Problem Description

Currently, Backend/db/chromadb/chroma.sqlite3 is tracked in version control. This causes the file to appear as "modified" in git status after every backend run, leading to constant merge conflicts for contributors and unnecessary repository bloat.

Evidence

Every time the backend runs, Backend/agent/vector_store.py initializes chromadb.PersistentClient(path="db/chromadb"), which modifies the SQLite binary file at runtime.

Proposed Solution

1. Stop Tracking: Run git rm --cached Backend/db/chromadb/chroma.sqlite3 to remove the file from the remote repo while keeping it locally for current users.
2. Ignore Future Changes: Update Backend/.gitignore to strictly exclude ChromaDB runtime files:

   # ChromaDB
   db/chromadb/*.sqlite3
   db/chromadb/*.sqlite3-shm
   db/chromadb/*.sqlite3-wal

3.Add a README note that the DB auto-initializes on first run.

Does the committed chroma.sqlite3 contain required seed data?
if Yes: I will add a Python seeding script.
if No: I will remove the binary file.

Please assign this issue to me, ready to implement.