feat: add Chrome tab group tools (create/update/add_tabs/close/list)

[gkrdl]

Summary

Adds five tools that wrap the Chrome tabs.group / tabGroups APIs so MCP clients can organize their automation tabs into named, collapsed groups instead of leaving loose tabs in the user's daily window.

Tools added

Tool	Args	Purpose
chrome_tab_group_create	tabIds, title?, color?, windowId?	Create a new group from existing tabs. Returns groupId.
chrome_tab_group_update	groupId, title?, color?, collapsed?	Rename / recolor / collapse / expand a group.
chrome_tab_group_add_tabs	groupId, tabIds	Add more tabs to an existing group.
chrome_tab_group_close	groupId	Close all tabs in a group (group disappears when empty).
chrome_tab_group_list	windowId?, color?, title?, collapsed?	Enumerate groups (returns enriched entries with tabIds).

A new tabGroups permission has been added to the extension manifest.

Why this matters

Without these, an MCP client running multi-tab research (price comparison, multi-source lookup, etc.) leaves a pile of tabs in the user's main window, and the user has to close them one by one. With grouping, the client can:

1. Open N tabs with `background: true`.
2. `chrome_tab_group_create` → `chrome_tab_group_update { collapsed: true }` → only the group label shows in the tab bar.
3. Extract data in parallel from each tab.
4. `chrome_tab_group_close` → all tabs gone in one call.

End-user impact: their daily window stays clean during automation, and they can collapse/expand the group on their own to review what the agent is doing.

Verification

• `pnpm build:shared`, `pnpm build:extension`, `pnpm build:native` all pass.
• Built extension manifest confirmed to include `tabGroups` permission and the five new tool names.
• Live test on macOS Chrome: opened 5 search-result tabs in `background: true`, called `chrome_tab_group_create` (got groupId), called `chrome_tab_group_update { collapsed: true }` (group collapsed in the tab bar without disturbing the active tab), called `chrome_javascript` against each grouped tab to extract data in parallel — all worked. The "active tab cannot be collapsed" Chrome quirk is documented in the schema.

Notes

• The "active tab cannot be collapsed" restriction is a Chrome behavior, not an MCP one. The collapse pattern works as long as the tabs were opened with `background: true` (which is the recommended pattern for automation tabs anyway).
• `chrome_tab_group_list` returns enriched entries (group metadata + tabIds in that group) so callers don't need a separate `chrome.tabs.query` round-trip.
• The new permission requires the user to accept a prompt on extension reload.