Polish component search explanations

[Mbeaulne]

Description

Introduces a dedicated componentSearchExplanations service that centralises the human-readable labels for matched search fields and a formatMatchedFieldsExplanation helper that converts a list of MatchField values into a natural-language sentence (e.g. "Matched name, inputs/outputs, and metadata."). The MATCH_FIELD_LABEL map that previously lived inline in DashboardComponentsV2View has been removed in favour of the shared COMPONENT_SEARCH_MATCH_FIELD_LABEL export.

Both ComponentCard (dashboard) and ComponentMarkup (sidebar) now show a "Why: …" explanation for lexical matches, falling back to the AI rerank reason when one is present. Previously only AI-reranked results showed this explanation.

The no-results message in both the dashboard and the editor sidebar has been split into two lines: a concise "No components matched …" sentence followed by actionable guidance on what kinds of terms to try.

matchedFields is now threaded through ComponentSearchV2Result and ComponentSearchResults so the sidebar can render per-field match explanations alongside rerank metadata.

Related Issue and Pull requests

Type of Change

• Bug fix
• New feature
• Improvement
• Cleanup/Refactor
• Breaking change
• Documentation update

Checklist

• I have tested this does not break current pipelines / runs functionality
• I have tested the changes on staging

Screenshots (if applicable)

Test Instructions

1. Open the component search in the dashboard or editor sidebar and type a query that matches components lexically (e.g. "standard" or "csv").
2. Confirm that each result shows a "Why: Matched …" line describing which fields matched.
3. Type a query that returns no results (e.g. "no-such-component") and confirm the two-line no-results guidance appears.
4. Configure AI search and confirm that AI rerank reasons still take precedence over the lexical explanation.

Additional Comments

The formatMatchedFieldsExplanation helper deduplicates field labels before joining them, so repeated entries in matchedFields do not produce malformed output.

[github-actions]

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A preview build has been created at: 06-23-polish_component_search_explanations/4bd0a11

[Mbeaulne]

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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

• Fix reasoning continuity and inline agent errors in chat #2462
• Add AI model quick-select to app menu and injectable model config #2461
• Simplify component search result cards #2459
• Add context-aware component search suggestions #2458
• Add component discovery docs #2457
• Add component search analytics baseline #2456
• Limit dashboard component browse rendering #2454
• Add component search empty state suggestions #2453
• Decouple editor component search input #2452
• Polish component search explanations #2451 👈 (View in Graphite)
• Add compatible component suggestions #2450
• Add component collection search results #2449
• Add component lifecycle badges #2448
• Add component search URL state #2447
• Disable AI search when literal search finds no matches #2444
• Debounce component search input #2433
• add client-side embeddings cached in IndexedDB #2432
• Add search quality expectation tests for lexical search #2431
• Add deep AI search to rerank all components in selected sources #2430
• Add source-diverse AI rerank candidate pool #2429
• Add negative constraint parsing to lexical search #2428
• Add fuzzy/typo-tolerant matching for component name and I/O fields #2427
• Improve component search scoring relevance #2426
• Add synonym expansion to component lexical search #2425
• Normalize component search tokens for better matching #2424
• Expand component search indexing fields #2423
• master

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