fix(mobile): unblock file tree and git commit input on touch devices

[schrodienieur]

Summary

On phones/tablets (max-width: 767px), the mobile layout shows full-screen panels (explorer / git / projects / settings) switched via the bottom nav — there is no desktop-style sidebar. Two bugs made those panels unusable on touch:

1. Taps and scroll gestures on the file tree / git commit box were swallowed. The editor panel (.workspace-center) is position:absolute; inset:0 and paints after the other panels in DOM order, so with default pointer-events:auto it silently covers them and eats touch input.
2. Long-press highlighted text / popped the context menu. A long-press on a tree row or editor tab triggered the native text-selection callout (highlighting labels like the bottom-nav "Files") and opened 9ed's context menu at the finger position, blocking scrolling and further taps.

Bug demo

The screen recording below shows the first symptom on a real device: a drag/scroll gesture on the file tree leaves the list completely static — the gesture never reaches the tree's scroll container because the overlapping editor panel intercepts it. The fix removes .workspace-center from the hit-test path in panel-based views, so scroll and tap events reach the file tree (verified: tapping a folder expands it, and the tree scrolls).

VID_20260813_075536.mp4

Changes

• frontend/src/styles/ide/overlays.css — in mobile panel-based views (explorer / projects / git / settings), set .workspace-center to pointer-events:none so taps reach the active panel; restored only in the editor view.
• frontend/src/styles/ide/base.css — IDE chrome (activity bar, panels, bottom nav, tabs, chat, terminal, picker, browser panel) is now user-select:none + -webkit-touch-callout:none, so long-press never starts a native selection; Monaco editor content stays selectable.
• frontend/src/components/sidebar/FileTree.tsx & frontend/src/components/editor/EditorTabs.tsx — context menu only opens on a real mouse right-click (or macOS Ctrl/Cmd+click); touch/pen contextmenu is ignored so a long-press doesn't pop the menu over the UI.
• frontend/src/styles/ide/file-tree.css — .tree-row gets user-select:none, touch-action:manipulation, -webkit-tap-highlight-color:transparent; on coarse-pointer devices rows get ~40px tap targets while desktop density is unchanged.

Verification

Tested with real touch events (CDP Input.dispatchTouchEvent with mobile emulation) against the built app:

• Tap a folder → expands (94 → 107 rows) ✅
• Long-press → selects nothing, opens no menu ✅
• Git commit textarea → focuses and accepts input ✅

No backend changes. Desktop behavior is unchanged (context-menu guard passes through real right-clicks; chrome no-select scoped to IDE chrome, editor still selectable).