Feature/issue 132 repository metadata

[Yuva-Deekshitha-N]

Resolves #132

Description

• Added repository-level metadata storage in .index_cache.json under the _metadata key

• Exposed metadata via a new GET /metadata endpoint in main.py

• Updated README with metadata fields table and example response

Related Issue

Fixes #132

Type of Change

• New feature
• Enhancement
• Documentation update

Changes Made

• indexer.py — stores repository_name, indexing_timestamp, indexed_file_count, embedding_model, and embedding_version into .index_cache.json after indexing

• main.py — added GET /metadata endpoint that reads and returns the _metadata block from the cache

• retriever.py — reads metadata from cache where needed

• README.md — added Repository Metadata section with field descriptions and example curl response

Testing

• Tested locally
• Existing tests pass
• Added new tests (if applicable)

Additional Notes:

• Verified GET /metadata returns correct JSON after running python indexer.py. Existing indexing and search flow unaffected.

Checklist

• My code follows the project's coding style.
• I have linked the related issue.
• I have tested my changes.
• I have updated documentation where necessary.
• My changes do not introduce new warnings or errors.
• The project builds successfully.
• This PR only addresses the linked issue.