Add BYOK component search settings hook

[Mbeaulne]

Tophatting

No manual tophatting required. This PR only adds the settings storage hook and unit tests.

What changed

Adds a small settings hook for Components V2 AI search configuration.

The hook stores these values in browser localStorage:

• API base URL
• API key
• model id

It also handles old saved config that used thinkingModel.

Why

AI search uses a bring-your-own-key setup. This PR only adds the storage layer; it does not add UI or call an AI provider yet.

Test plan

• Run pnpm exec vitest run src/hooks/useComponentSearchSettings.test.ts
• Run pnpm run typecheck --pretty false
• Confirm empty settings report as not configured
• Confirm saved settings load back from localStorage

[Mbeaulne]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• Add AI rerank and detail actions to Components V2 #2323
• Add multi-source Components V2 search and filters #2322
• Add Components V2 route shell #2319
• Add component search support utilities #2318
• Extract shared component detail view #2317
• Add natural-language component rerank service #2321
• Add Agent Settings UI for AI search #2320
• Add BYOK component search settings hook #2316 👈 (View in Graphite)
• Add component search index service #2315
• master

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[github-actions]

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