Restructure app-desktop as self-contained package, add PyInstaller build

Consolidates everything the desktop app depends on into app-desktop/ so it
packages cleanly as a standalone Windows exe:

- app-desktop-macos/ -> app-desktop/src/ (drop macOS-only naming, app now
  targets Windows via PyInstaller too)
- remote-server/ws_server.py and app-presets/ moved into app-desktop/src/
  (both were exclusive dependencies of main.py/presets.py) — fixes a
  PyInstaller "missing module" error for ws_server that only surfaced once
  packaging was attempted, since its old location wasn't on the analyzer's
  search path
- .venv relocated into app-desktop/src/ alongside the code it serves
- run.py moved into src/, path logic simplified now that it's co-located
  with main.py instead of bridging from the repo root
- Deleted app/, server/ — stale __pycache__-only fossils from prior reorgs
- .gitignore: added missing .venv/ entry (was only covering venv/, a
  different name — the real folder was never actually ignored) and
  app-desktop/build|dist/ for PyInstaller output

presets.py: added a frozen-vs-source branch. Running from source is
unchanged (app-presets/ next to the code). A packaged exe can't write to
Program Files, so it uses %APPDATA%\VirtualController\ instead — standard
Windows convention. First launch on a machine with no AppData presets yet
seeds from presets.json bundled into the exe (PyInstaller --add-data,
baked into VirtualController.spec), so a fresh install starts with real
presets instead of empty; every launch after that only touches AppData.

Verified: exe builds clean (no missing-module warnings), launches with a
real window, and a clean first-launch correctly seeds AppData from the
bundled presets.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app-desktop/VirtualController.spec

@@ -0,0 +1,44 @@
+# -*- mode: python ; coding: utf-8 -*-
+
+
+a = Analysis(
+    ['src\\main.py'],
+    pathex=[],
+    binaries=[],
+    datas=[('src/app-presets/presets.json', 'app-presets')],
+    hiddenimports=[],
+    hookspath=[],
+    hooksconfig={},
+    runtime_hooks=[],
+    excludes=[],
+    noarchive=False,
+    optimize=0,
+)
+pyz = PYZ(a.pure)
+
+exe = EXE(
+    pyz,
+    a.scripts,
+    [],
+    exclude_binaries=True,
+    name='VirtualController',
+    debug=False,
+    bootloader_ignore_signals=False,
+    strip=False,
+    upx=True,
+    console=False,
+    disable_windowed_traceback=False,
+    argv_emulation=False,
+    target_arch=None,
+    codesign_identity=None,
+    entitlements_file=None,
+)
+coll = COLLECT(
+    exe,
+    a.binaries,
+    a.datas,
+    strip=False,
+    upx=True,
+    upx_exclude=[],
+    name='VirtualController',
+)