Add desktop dialogs framework (#5605)

### Summary

Adds desktop dialog framework with data-driven dialog definitions.

### Changes

- Data-driven dialog structure in `desktopDialogs.ts`
- Dynamic dialog view component with i18n support
- Button action types: openUrl, close, cancel
- Button severity levels for styling (primary, secondary, danger, warn)
- Fallback invalid dialog for error handling
- i18n collection script updated for dialog strings

src/constants/desktopDialogs.ts

@@ -0,0 +1,75 @@
+export interface DialogAction {
+  readonly label: string
+  readonly action: 'openUrl' | 'close' | 'cancel'
+  readonly url?: string
+  readonly severity?: 'danger' | 'primary' | 'secondary' | 'warn'
+  readonly returnValue: string
+}
+
+interface DesktopDialog {
+  readonly title: string
+  readonly message: string
+  readonly buttons: DialogAction[]
+}
+
+export const DESKTOP_DIALOGS = {
+  /** Shown when a corrupt venv is detected. */
+  reinstallVenv: {
+    title: 'Reinstall ComfyUI (Fresh Start)?',
+    message: `Sorry, we can't launch ComfyUI because some installed packages aren't compatible.
+
+Click Reinstall to restore ComfyUI and get back up and running.
+
+Please note: if you've added custom nodes, you'll need to reinstall them after this process.`,
+    buttons: [
+      {
+        label: 'Learn More',
+        action: 'openUrl',
+        url: 'https://docs.comfy.org',
+        returnValue: 'openDocs'
+      },
+      {
+        label: 'Reinstall',
+        action: 'close',
+        severity: 'danger',
+        returnValue: 'resetVenv'
+      }
+    ]
+  },
+  /** A dialog that is shown when an invalid dialog ID is provided. */
+  invalidDialog: {
+    title: 'Invalid Dialog',
+    message: `Invalid dialog ID was provided.`,
+    buttons: [
+      {
+        label: 'Close',
+        action: 'cancel',
+        returnValue: 'cancel'
+      }
+    ]
+  }
+} as const satisfies { [K: string]: DesktopDialog }
+
+/** The ID of a desktop dialog. */
+type DesktopDialogId = keyof typeof DESKTOP_DIALOGS
+
+/**
+ * Checks if {@link id} is a valid dialog ID.
+ * @param id The string to check
+ * @returns `true` if the ID is a valid dialog ID, otherwise `false`
+ */
+function isDialogId(id: unknown): id is DesktopDialogId {
+  return typeof id === 'string' && id in DESKTOP_DIALOGS
+}
+
+/**
+ * Gets the dialog with the given ID.
+ * @param dialogId The ID of the dialog to get
+ * @returns The dialog with the given ID
+ */
+export function getDialog(
+  dialogId: string | string[]
+): DesktopDialog & { id: DesktopDialogId } {
+  const id = isDialogId(dialogId) ? dialogId : 'invalidDialog'
+  return { id, ...structuredClone(DESKTOP_DIALOGS[id]) }
+}