Added PostgreSQL implementation

[ShanGor]

With PostgreSQL as one stop solution for storage.

• Doc status storage
• KV storage
• Vector storage (pgvector)
• Graph storage (Apache AGE). It is a new implementation with asyncpg, share the connection pool.

The implementation is tested with script: examples/lightrag_zhipu_postgres_demo.py

Why? PG is lightweight, the whole binary distribution including all necessary plugins can be zipped to 40MB: Ref to release

[LarFii]

Thanks for your contribution! But there are some linting errors. Please make sure to run pre-commit run --all-files before submitting to ensure all linting checks pass. Also, could you please modify the comments to be in English to facilitate future development? Thanks again!

[ShanGor]

Thanks for your contribution! But there are some linting errors. Please make sure to run pre-commit run --all-files before submitting to ensure all linting checks pass. Also, could you please modify the comments to be in English to facilitate future development? Thanks again!

thanks, i will fix and resubmit.

[ShanGor]

Thanks for your contribution! But there are some linting errors. Please make sure to run pre-commit run --all-files before submitting to ensure all linting checks pass. Also, could you please modify the comments to be in English to facilitate future development? Thanks again!

Hi @LarFii, done the fix and all checks have passed.

[LarFii]

Thanks!