⚡ Optimize importChromeTabGroups to avoid N+1 queries

[Matuyuhi]

💡 What: Replaced the loop querying tabs per groupId inside importChromeTabGroups with a single upfront chrome.tabs.query({ windowId }) fetch. Tabs are grouped into a Map for fast lookup.

🎯 Why: To eliminate severe N+1 scaling performance issues during space imports containing multiple tab groups. Furthermore, the await loadStore call and iteration computing claimed IDs were redundant on each iteration and have been extracted outside of the loop.

📊 Measured Improvement: Utilizing a simulated IPC delay benchmark script test_perf.ts (with an artificial 1ms delay for each call) with 500 mock groups:

• Baseline: ~750 ms
• Optimized: ~4.5 ms
  The change provides nearly constant-time scaling regardless of the number of Tab Groups present, limited only by the upfront single query of all tabs in the window.

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PR created automatically by Jules for task 5633793021932842105 started by @Matuyuhi

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