fix: preserve API prefix in session Location header (fixes #247)

[Flamki]

Fixes #247.

Description

start_chat was setting Location via a hardcoded path (/sessions/{id}/message), which ignores the API router prefix when mounted (default: /api/chatbot).

This PR switches Location generation to route resolution so the header always matches mounted routes.

Changes

• chatbot-core/api/routes/chatbot.py
  • add Request parameter to start_chat
  • replace hardcoded Location with:
    • request.url_for("chatbot_reply", session_id=session_id).path
• chatbot-core/tests/unit/routes/test_chatbot.py
  • add regression test test_start_chat_location_includes_router_prefix
  • keep existing non-prefixed behavior test

Why this is aligned / scoped

• Small backend correctness fix
• No architecture or auth design changes
• Improves API contract reliability for clients following Location

Testing done

• pytest tests/unit/routes/test_chatbot.py -q -> 7 passed
• pylint api/routes/chatbot.py tests/unit/routes/test_chatbot.py -> 10.00/10

Submitter checklist

• Topic branch used
• PR title represents intended changelog entry
• Changes described
• Linked issue
• Added regression test

[berviantoleo]

You should change this line, instead of creating a new test

[berviantoleo]

Use parametrize if necessary

https://docs.pytest.org/en/stable/how-to/parametrize.html

[berviantoleo]

In my mind, I thought Location would be used by UI to navigate the page.

https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Location

Content-Location may be more appropriate

https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Content-Location

[sharma-sugurthi]

Location on a 201 should point to the created resource itself (/sessions/{id}), not the action endpoint (/sessions/{id}/message). Content-Location fits better here since it's telling the client where to send messages next rather than identifying the resource itself. @Flamki ,its just suggestions...But nice fix bro..