feat: Wave 3 — plugin loader + Flet GUI (parity with Rust fork)

Plugin loader (mirrors Rust #29):
- plugins_store.py walks %APPDATA%\com.priler.jarvis\plugins\<name>\
  for commands.yaml fragments and merges them into VA_CMD_LIST at
  startup. Same schema as the project root commands.yaml. Per-pack
  `disabled` flag file skips a pack without deletion. Built-in ids
  win conflicts so a malicious pack can't silently override
  open_browser. 9 unit tests (parity with the Rust tests).
- main.py: plugin merge runs after the root yaml load; logs the
  number of extra commands picked up.

Flet GUI (#27 — first parity with the Rust Tauri GUI):
- New gui/ package: __main__.py launches via `python -m gui` (or
  gui.bat). app.py routes between 7 pages (Главная / Команды /
  Макросы / Расписание / Память / Плагины / Настройки) via
  NavigationRail; dark theme matching the Tauri look.
- gui/services.py centralises every store-module call the pages
  share — single place to swap implementations later.
- One file per page in gui/pages/, all expose `build(page)` and use
  the same card layout idiom. Pages mirror the Tauri ones feature-
  for-feature: home (status + counters + launcher), commands
  (filterable list of all VA_CMD_LIST entries), macros (list +
  delete + recording banner), scheduler (list + remove), memory
  (add/forget/search), plugins (toggle/open folder), settings
  (profile + LLM hot-swap).
- requirements.txt: flet>=0.85 (optional; assistant runs without).
- 3 smoke tests verify imports + build callables; skip cleanly when
  Flet isn't installed.

README: documents both the GUI and the plugin layout in user-facing
terms. Tests: 42 → 54 (+9 plugins +3 GUI smoke).

gui/pages/home.py

@@ -0,0 +1,119 @@
+"""Home page — quick launcher + active backends + counters."""
+
+import flet as ft
+
+from gui import services as svc
+
+
+def _stat_card(title: str, value: str, color: str = "#33d3a4") -> ft.Container:
+    return ft.Container(
+        content=ft.Column(
+            [
+                ft.Text(title, size=11, color="#8aa0a8"),
+                ft.Text(value, size=22, weight=ft.FontWeight.W_600, color=color),
+            ],
+            spacing=2,
+        ),
+        bgcolor="#15252b",
+        border_radius=10,
+        padding=14,
+        expand=True,
+    )
+
+
+def build(page: ft.Page) -> ft.Control:
+    running = svc.assistant_is_running()
+    try:
+        llm_b, llm_m = svc.llm_active()
+    except (RuntimeError, OSError, ValueError) as exc:
+        llm_b, llm_m = "—", str(exc)
+
+    counters = ft.Row(
+        controls=[
+            _stat_card("Команды", str(_safe_count(svc, "commands"))),
+            _stat_card("Макросы", str(len(svc.macros_all()))),
+            _stat_card("Расписание", str(len(svc.scheduler_all()))),
+            _stat_card("Память (фактов)", str(len(svc.memory_all()))),
+            _stat_card("Плагины", str(len(svc.plugins_all()))),
+        ],
+        spacing=10,
+    )
+
+    status_chip = ft.Container(
+        content=ft.Text(
+            "АССИСТЕНТ РАБОТАЕТ" if running else "АССИСТЕНТ ОСТАНОВЛЕН",
+            size=12,
+            weight=ft.FontWeight.W_700,
+            color="#13191c",
+        ),
+        bgcolor="#33d3a4" if running else "#d8d8d8",
+        padding=ft.padding.symmetric(horizontal=12, vertical=6),
+        border_radius=20,
+    )
+
+    start_btn = ft.FilledButton(
+        text="Запустить J.A.R.V.I.S.",
+        icon=ft.Icons.PLAY_ARROW,
+        on_click=lambda e: _launch(page, e),
+        disabled=running,
+    )
+
+    backends_card = ft.Container(
+        content=ft.Column([
+            ft.Text("Активный LLM", size=11, color="#8aa0a8"),
+            ft.Text(f"{llm_b} · {llm_m}", size=14, weight=ft.FontWeight.W_500),
+        ], spacing=2),
+        bgcolor="#15252b",
+        border_radius=10,
+        padding=14,
+    )
+
+    return ft.Column(
+        controls=[
+            ft.Row([
+                ft.Text("J.A.R.V.I.S.", size=28, weight=ft.FontWeight.W_700),
+                status_chip,
+            ], alignment=ft.MainAxisAlignment.SPACE_BETWEEN),
+            ft.Text(
+                "Голосовой ассистент — Python-форк. Эта панель управляет состоянием, "
+                "запускает main.py и переключает движки.",
+                color="#8aa0a8",
+                size=12,
+            ),
+            ft.Divider(color="#1f3540"),
+            backends_card,
+            counters,
+            ft.Divider(color="#1f3540"),
+            start_btn,
+        ],
+        spacing=14,
+        expand=True,
+        scroll=ft.ScrollMode.AUTO,
+    )
+
+
+def _launch(page: ft.Page, _e) -> None:
+    ok = svc.assistant_run()
+    page.open(
+        ft.SnackBar(
+            content=ft.Text(
+                "Запускаю main.py" if ok else "Не удалось запустить main.py",
+                color="white",
+            ),
+            bgcolor="#33d3a4" if ok else "#d8584f",
+        )
+    )
+
+
+def _safe_count(svc_module, kind: str) -> int:
+    """Counts come from disk; if a store fails we display 0 rather than crash."""
+    try:
+        if kind == "commands":
+            # Don't import the full VA_CMD_LIST machinery — read yaml directly.
+            import os, yaml  # pylint: disable=import-outside-toplevel
+            here = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+            with open(os.path.join(here, "commands.yaml"), "rt", encoding="utf8") as f:
+                return len(yaml.safe_load(f) or {})
+    except (OSError, ValueError):
+        return 0
+    return 0