refactor(client): remove Python embedded mode

[qin-ctx]

Description

Remove the public in-process Python embedded mode and consolidate Python consumers on the supported HTTP SDK. The shared HTTP Server, Service layer, storage backends, and VectorDB capabilities remain unchanged.

Human Involvement

• A human participated in the implementation or review loop
• This PR was generated entirely by AI agents without human participation in the loop

Related Issue

N/A

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactoring (no functional changes)
• Performance improvement
• Test update

Changes Made

• Remove AsyncOpenViking, SyncOpenViking/OpenViking, LocalClient, and their embedded-only session and snapshot wrappers.
• Migrate examples, benchmarks, RAGAS, FUSE, and LangChain integration paths to the Python HTTP SDK or the shared Service layer where tests target domain behavior.
• Remove embedded-only tests and documentation while preserving HTTP Server, Service, storage, and VectorDB functionality.

Testing

• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have tested this on the following platforms:
  • Linux
  • macOS
  • Windows

Checklist

• My code follows the project's coding style
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published

Screenshots (if applicable)

N/A

Additional Notes

No tests were added; embedded-only tests were deleted and shared Service contract tests were updated. Focused validation completed with 139 tests passing and 12 optional-dependency skips.