Docs: add single-file upload, file status, and file delete sections

[parag]

Summary

Doc sections covering single-file upload, file indexing status, and file delete were written locally on a private branch and have been reverted as unauthorized work. Refile here so they can be rebuilt cleanly alongside the approved SDK methods.

Sections to write

Uploading guide (src/content/docs/files/uploading.mdx)

Add three sections after the existing folder-sync explanation:

1. Single-file upload — POST /v1/files flow with SDK and curl examples. Explain when to prefer this over folder sync (ad-hoc files, non-filesystem sources, programmatic intake).
2. Checking file status — GET /v1/files/:path/status with a polling example. Cover the four states (pending, indexing, ready, failed) and what they mean.
3. Deleting a file — DELETE /v1/files/:path with cascade behavior on associated memories. Warn that deletion is irreversible.

SDK client references

Add matching method entries to both:

• src/content/docs/python/client-reference.mdx — upload, file_status, delete_file
• src/content/docs/typescript/client-reference.mdx — upload, fileStatus, deleteFile

Each entry should show signature, parameters, return shape, and a one-line example.

Scope approximation

~90 lines added to uploading.mdx, ~26 lines per SDK reference. Total around 140 lines across 3 files based on the reverted patch.

Cross-repo tracking

• TypeScript SDK methods: hebbs-ai/hebbs-typescript companion issue.
• Python SDK methods: hebbs-ai/hebbs-python companion issue.
• Server endpoints live in the private hebbs-platform service.