feat(workbench): Open files from Finder in the single-file window (#152)

On macOS, OpenIDEA is now listed under Finder's Open With for text and source files and for folders. It never becomes the default app for any of them: all document types are declared with rank Alternate, and only in tauri.macos.conf.json, so Windows and Linux installers register nothing.

Files opened from Finder, the Dock or a second instance share one routing path (plan_open). A file inside a local project that is already open, or still opening, goes to that project's window, choosing the deepest root when projects are nested. Any other file goes to the existing single-file window, or to a new one. A folder focuses the window that already has it open, otherwise it opens as a project. Paths that arrive before setup are queued and opened with the first launch.

The single-file window now closes with its last tab, restores its files the next time it opens, and only offers Open File and drop hints when empty. Also fixes a regression: reopening projects on startup no longer replaces a file opened at cold start.

Refs #128

src/editor/core/controller.ts

@@ -102,6 +102,9 @@ export function isTextInput(input: EditorInput): input is EditorInput & { path:
 
 export const useTabs = create<TabsState>(() => initialTabsState());
 
+/** Session key of the LightEdit window: its tabs reopen the next time a window switches to LightEdit. */
+export const LIGHT_EDIT_SESSION = "<lightEdit>";
+
 export interface EditorStatus {
   path: string;
   doc: number;
@@ -179,7 +182,7 @@ export class EditorController implements SlotHost {
   activeSlot: EditorSlot | null = null;
   private statusScheduled = false;
   private disposers: Array<() => void> = [];
-  /** Project root whose editor session is being tracked (null while switching). */
+  /** Project root (or {@link LIGHT_EDIT_SESSION}) whose editor session is being tracked (null while switching). */
   private sessionRoot: string | null = null;
   private sessionTimer: ReturnType<typeof setTimeout> | undefined;
   /** Restored caret / scroll per path, applied when the file's first slot is created. */
@@ -237,6 +240,7 @@ export class EditorController implements SlotHost {
           this.nav.clear();
           this.edits.clear();
           if (root) this.restoreSession(root);
+          else if (s.lightEdit) this.restoreSession(LIGHT_EDIT_SESSION);
         }
       }),
     );