🧹 refactor: Extract suggestion logic from CommandBar.svelte

[undivisible]

🎯 What: Extracted the suggestion logic from CommandBar.svelte into a new suggestions.ts utility file.
💡 Why: CommandBar.svelte was extremely long and conflated UI markup with complex fuzzy search, filtering, and scoring logic. Extracting this improves readability and allows unit testing the suggestion algorithms without mounting the component.
✅ Verification: Ran bun run check locally to ensure zero Svelte compilation or typing errors. Re-verified store reactivity by explicitly passing stores ({ browser, tabCounts }) to $: reactive declarations. Verified no unresolved imports.
✨ Result: A leaner CommandBar.svelte focused purely on UI orchestration. No behavioral changes.

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PR created automatically by Jules for task 8566463460012556513 started by @undivisible

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