feat(scheduler): IMBA-5 proactive scheduler — reminders, daily briefings, intervals

Background thread that wakes J.A.R.V.I.S. on a schedule to speak reminders.
Nothing else competes here on desktop — Алиса/Сири are reactive-only.

Core (crates/jarvis-core/src/scheduler.rs)
  - Schedule::{Daily{h,m}, Interval{secs}, Once{at}} with Schedule::parse for
    "daily HH:MM" / "at HH:MM" / "every N minutes|hours" / "in N minutes|hours".
    Russian units (час/часа/часов/минут/секунд) also accepted.
  - ScheduledTask {id, name, schedule, action, last_fired, enabled, created_at}.
    Action::Speak{text} | Action::Lua{script_path}.
  - JSON persistence at <APP_CONFIG_DIR>/schedule.json, atomic write-through.
  - add/remove/clear/list/find; mark_fired auto-deletes Once tasks.
  - start_background() spawns a 30-second tick thread (idempotent). Each tick
    calls due_tasks(), fires Action via tts::speak_default (after voices::play_reply
    "ahem" cue) or Lua engine.
  - 7 unit tests (all passing).

Lua API (crates/jarvis-core/src/lua/api/scheduler.rs)
  - jarvis.scheduler.add({name, schedule, action={type, text|script_path}})
  - jarvis.scheduler.{list, count, remove(id), clear}.
  - Tasks come back as {id, name, schedule_human, action, enabled, last_fired}.

Wire-up (crates/jarvis-app/src/main.rs)
  - scheduler::init() + scheduler::start_background() after profiles::init.
  - Tasks survive restarts via schedule.json.

Voice commands (resources/commands/scheduler/, 6 ids)
  - scheduler.add_reminder    "напомни через 5 минут выключить кофеварку"
  - scheduler.add_at          "напомни в 18:00 забрать ребёнка"
  - scheduler.add_recurring   "каждые 2 часа напоминай попить воды"
  - scheduler.add_daily       "каждый день в 9:00 делай briefing"
  - scheduler.list            "что у меня запланировано"
  - scheduler.clear           "очисти расписание"

Russian-aware parsers (час/часа/часов, минут/минуту/минуты) live inside the Lua
packs — easy to extend without touching Rust.

Tests: 31/31 jarvis-core unit tests pass (24 prior + 7 scheduler).
Build: cargo build --release -p jarvis-app and -p jarvis-gui both green.

crates/jarvis-core/src/lua/engine.rs

@@ -80,6 +80,7 @@ impl LuaEngine {
         api::text::register(&self.lua, &jarvis)?;
         api::memory::register(&self.lua, &jarvis)?;
         api::profile::register(&self.lua, &jarvis)?;
+        api::scheduler::register(&self.lua, &jarvis)?;
 
         // sandbox-controlled APIs
         if self.sandbox.allows_http() {