feat: add Firefox extension support

- Add Firefox as an install target with native messaging manifest support.
- Generate Firefox-specific extension packages with Gecko metadata and AMO-compatible manifest transforms.
- Keep tab group commands available in Firefox through dynamic tab group API helpers.
- Avoid Firefox linter warnings for static tab group API references and direct eval tokens.
- Add Firefox packaging and installer regression coverage.
- Bump the package and extension version to 0.15.1.

extension/src/commands/tabs.ts

@@ -1,4 +1,4 @@
-import { asTabIds, getActiveTab, getLargeOperationThrottle, processInBatches, resolveTabForDirectAction, runLargeOperation, throwIfJobCancelled, updateJobProgress, yieldForLargeOperation } from '../core';
+import { asTabIds, getActiveTab, getLargeOperationThrottle, groupTabs, processInBatches, resolveTabForDirectAction, runLargeOperation, throwIfJobCancelled, updateJobProgress, yieldForLargeOperation } from '../core';
 import { CommandGroup } from '../classes/CommandGroup';
 import type { CommandEntry } from '../classes/CommandGroup';
 import type { TabsCloseArgs, TabsMoveArgs, TabIdArgs, TabsSortArgs, TabsMergeWindowsArgs, TabsScreenshotArgs } from '../types';
@@ -64,7 +64,7 @@ export class TabsMutationCommands extends CommandGroup {
     // `index` is always assigned by one of the branches above before this call.
     await chrome.tabs.move(tabId, moveProps as chrome.tabs.MoveProperties);
     if (groupId != null) {
-      await chrome.tabs.group({ tabIds: asTabIds([tabId]), groupId });
+      await groupTabs({ tabIds: asTabIds([tabId]), groupId });
     }
     return { tabId };
   }