feat: hide dotfiles in file explorer (#1516)

* feat: hide dotfiles in file explorer

* refactor: rename to "hidden files" and read flag from store

Rename the explorer dotfile toggle to show-semantics "hidden files"
so copy and code share one cross-platform vocabulary, and stop
prop-drilling the flag now that it lives in the panel store.

- explorerShowHiddenFiles (default true) replaces explorerHideDotFiles;
  i18n keys + translations switched from "dotfiles" to "hidden files"
- imperative helpers read usePanelStore.getState() instead of taking
  the flag as a parameter; flag stays threaded only through the
  reactive tree-row render path
- drop dead usePanelState exposure; collapse migration double-guard

* fix: address Greptile review on hidden-file path matching

- isHiddenExplorerPath no longer treats ".." segments as hidden
  (only "." was exempt before); add tests for ".." and "../sibling"
- assert the showHiddenFiles i18n key alongside hideHiddenFiles

---------

Co-authored-by: Mohamed Boudra <boudra.moha@gmail.com>

packages/app/src/stores/panel-store/state.ts

@@ -245,6 +245,9 @@ export function migratePanelState(
   ) {
     state.diffExpandedPathsByWorkspace = {};
   }
+  if (typeof state.explorerShowHiddenFiles !== "boolean") {
+    state.explorerShowHiddenFiles = true;
+  }
 
   return state;
 }