fix: use Tauri opener plugin for URL property clicks

Replace window.open() with Tauri's opener plugin (openUrl) so that
clicking a URL property in the Properties panel opens the system
browser instead of failing silently or triggering edit mode.

- Install @tauri-apps/plugin-opener (npm + Cargo + capabilities)
- Add openExternalUrl() utility with Tauri/browser fallback
- Add stopPropagation to prevent accidental edit mode activation
- Add double-click guard (500ms debounce via ref)
- Update tests to mock openExternalUrl instead of window.open
- Add explicit test that URL click does not trigger onStartEdit

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/EditableValue.test.tsx

@@ -3,6 +3,13 @@ import { render, screen, fireEvent } from '@testing-library/react'
 import { EditableValue, TagPillList, UrlValue } from './EditableValue'
 import { isUrlValue, normalizeUrl } from '../utils/url'
 
+vi.mock('../utils/url', async () => {
+  const actual = await vi.importActual('../utils/url')
+  return { ...actual, openExternalUrl: vi.fn().mockResolvedValue(undefined) }
+})
+
+const { openExternalUrl } = await import('../utils/url') as typeof import('../utils/url') & { openExternalUrl: ReturnType<typeof vi.fn> }
+
 describe('EditableValue', () => {
   const onSave = vi.fn()
   const onCancel = vi.fn()
@@ -219,28 +226,28 @@ describe('UrlValue', () => {
     expect(screen.getByTestId('url-link')).toHaveTextContent('https://example.com')
   })
 
-  it('opens URL in new tab on click', () => {
-    const openSpy = vi.spyOn(window, 'open').mockImplementation(() => null)
+  it('opens URL via openExternalUrl on click', () => {
     render(<UrlValue value="https://example.com" onSave={onSave} onCancel={onCancel} isEditing={false} onStartEdit={onStartEdit} />)
     fireEvent.click(screen.getByTestId('url-link'))
-    expect(openSpy).toHaveBeenCalledWith('https://example.com', '_blank')
-    openSpy.mockRestore()
+    expect(openExternalUrl).toHaveBeenCalledWith('https://example.com')
   })
 
   it('normalizes bare domain before opening', () => {
-    const openSpy = vi.spyOn(window, 'open').mockImplementation(() => null)
     render(<UrlValue value="example.com" onSave={onSave} onCancel={onCancel} isEditing={false} onStartEdit={onStartEdit} />)
     fireEvent.click(screen.getByTestId('url-link'))
-    expect(openSpy).toHaveBeenCalledWith('https://example.com', '_blank')
-    openSpy.mockRestore()
+    expect(openExternalUrl).toHaveBeenCalledWith('https://example.com')
   })
 
   it('does not open malformed URL', () => {
-    const openSpy = vi.spyOn(window, 'open').mockImplementation(() => null)
     render(<UrlValue value="://broken" onSave={onSave} onCancel={onCancel} isEditing={false} onStartEdit={onStartEdit} />)
     fireEvent.click(screen.getByTestId('url-link'))
-    expect(openSpy).not.toHaveBeenCalled()
-    openSpy.mockRestore()
+    expect(openExternalUrl).not.toHaveBeenCalled()
+  })
+
+  it('does not trigger edit mode when URL link is clicked', () => {
+    render(<UrlValue value="https://example.com" onSave={onSave} onCancel={onCancel} isEditing={false} onStartEdit={onStartEdit} />)
+    fireEvent.click(screen.getByTestId('url-link'))
+    expect(onStartEdit).not.toHaveBeenCalled()
   })
 
   it('shows edit button that calls onStartEdit', () => {

src/components/EditableValue.tsx

@@ -1,5 +1,5 @@
-import { useState, useCallback } from 'react'
-import { normalizeUrl } from '../utils/url'
+import { useState, useCallback, useRef } from 'react'
+import { normalizeUrl, openExternalUrl } from '../utils/url'
 
 export function UrlValue({
   value,
@@ -15,6 +15,7 @@ export function UrlValue({
   onStartEdit: () => void
 }) {
   const [editValue, setEditValue] = useState(value)
+  const openingRef = useRef(false)
 
   const handleKeyDown = (e: React.KeyboardEvent) => {
     if (e.key === 'Enter') {
@@ -25,16 +26,28 @@ export function UrlValue({
     }
   }
 
-  const handleOpen = useCallback(() => {
+  const handleOpen = useCallback((e: React.MouseEvent) => {
+    e.stopPropagation()
+    if (openingRef.current) return
+    openingRef.current = true
     const normalized = normalizeUrl(value)
     try {
       new URL(normalized)
-      window.open(normalized, '_blank')
+      openExternalUrl(normalized).catch(() => {
+        // opener failed — ignore silently
+      })
     } catch {
       // malformed URL — do nothing
+    } finally {
+      setTimeout(() => { openingRef.current = false }, 500)
     }
   }, [value])
 
+  const handleEditClick = useCallback((e: React.MouseEvent) => {
+    e.stopPropagation()
+    onStartEdit()
+  }, [onStartEdit])
+
   if (isEditing) {
     return (
       <input
@@ -61,7 +74,7 @@ export function UrlValue({
       </span>
       <button
         className="shrink-0 border-none bg-transparent p-0 text-[12px] leading-none text-muted-foreground opacity-0 transition-all hover:text-foreground group-hover/url:opacity-100"
-        onClick={onStartEdit}
+        onClick={handleEditClick}
         title="Edit URL"
         data-testid="url-edit-btn"
       >