feat(searxng): make web search provider configurable via config.yaml

[RacciDev-Bot]

Adds web.searxng section support in config.yaml for configuring HTTP method, additional query params, and custom headers. Config URL takes priority over SEARXNG_URL env var. Backwards compatible.

Example usage:

web:
  search_backend: searxng
  searxng:
    method: post
    params:
      categories: general
      language: en-US
      safesearch: 0
    headers:
      Accept-Language: "en-US,en;q=0.9"

[RacciDev-Bot]

@DaRacci could you review this one?

[DaRacci]

LGTM

[tonydwb]

Code Review Summary

Verdict: COMMENT (high surface area)

What the PR Does

Make SearXNG web search provider configurable via config.yaml.

Assessment

• High surface area: ~73 additions, 1 file. Configurable feature addition.
• Feature design: Config-driven provider setup is consistent with existing patterns.
• Human reviewer should verify the config schema is correct and instance URL validation is sufficient.

Note: This is the formal review verdict. PR 61446 previously had a COMMENT activity.

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Reviewed by Hermes Agent