Description

Tighten config validation across ov.conf and ovcli.conf so unknown fields fail fast with readable error messages instead of being silently ignored. This also prevalidates the full config during openviking-server --config ... startup and consolidates shared validation/error-formatting helpers into one utility module.

Related Issue

Fixes #855
Related prior PRs: #856, #881

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

• Added shared config validation helpers for typo suggestions and friendly Pydantic error formatting, and reused them across server, parser, and top-level OpenViking config loaders
• Made server, parser, top-level ov.conf, and ovcli.conf reject unknown fields with explicit error paths instead of silently ignoring them
• Validated the full config during openviking-server --config ... startup and added regression tests for friendly error messages and config precedence behavior

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

• This PR intentionally chooses strict validation for unknown fields, because warning-only behavior still leaves misconfigurations easy to miss.
• ovcli.conf now also supports filling in missing auth/context fields even when url is passed explicitly, while keeping explicit arguments higher priority than config values.
• Local verification command:
  env OPENVIKING_CONFIG_FILE=/tmp/codex-no-config.json .venv/bin/python -m pytest tests/client/test_http_client_config.py tests/test_config_loader.py tests/test_server_config_loader.py tests/parse/test_markdown_char_limit.py -q