test+feat: +37 tests (62→99) + intro/echo packs (5 new commands)

Major test coverage push: pins IPC wire format, scheduler parser/serde,
runtime_config env handling. Plus two debug/discovery packs.

Tests (62 → 99, +37)

IPC roundtrip (new file crates/jarvis-core/src/ipc/tests.rs, +19 tests)
  - Event tags use snake_case ("wake_word_detected", "speech_recognized", ...)
  - Idle event has minimal payload (tag only, no extra fields)
  - SpeechRecognized/LlmReply/Error carry their text payloads
  - CommandExecuted carries id + success bool
  - HealthSnapshot full shape: tts/llm/llm_model/profile/memory_facts/
    scheduled_tasks/language/version
  - HealthSnapshot handles llm_model:null / version:null
  - Cross-variant invariant: every event has snake-case "event" tag
  - Action parsing: stop / ping / text_command / set_muted / switch_llm /
    reload_llm / query_health
  - Unknown action variant errors out
  - switch_llm requires "backend" field (missing field errors)

runtime_config (was 2, now 11 tests, +9)
  - get_bool recognises 1/true/yes/on (case-insensitive)
  - get_bool falsifies 0/false/no/off/anything-else
  - get() strips whitespace, empty = unset
  - llm_router_threshold default 0.55 / custom parse / garbage fallback
  - llm_tts_enabled default true, recognises "false"
  - llm_router_enabled default true
  - Uses unique env var names per test to avoid thread races

scheduler (was 10, now 19 tests, +9)
  - parse_in_hours yields Once
  - parse_at_today_or_tomorrow
  - parse_at_rejects_bad_time (25:00, 12:99, "notatime")
  - parse_daily_rejects_bad_hour (24:00, 12:60)
  - parse_every_seconds
  - parse_unrecognised_spec_errors ("nonsense", "daily", "every")
  - task_serde_round_trip preserves last_fired + action variant
  - schedule_kind_tag_in_json pins {"kind":"daily","hour":...,"minute":...}
  - action_serde_lua_variant roundtrip

New packs

resources/commands/intro/ (3 commands)
  - intro.capabilities  "что ты умеешь" / "помощь" / "помоги"
                        → speaks a 7-line category overview
  - intro.about         "расскажи о себе" / "кто ты такой"
                        → LLM-varied bio with profile name
                        Falls back to canned text if LLM unavailable.
  - intro.commands_count "сколько команд знаешь"
                        → reads jarvis.health() and reports backends + counts

resources/commands/echo/ (2 commands)
  - echo.repeat         "повтори за мной X" → speaks X verbatim
                        Preserves original casing by re-grabbing from raw phrase.
  - echo.what_did_i_say "что я сказал" → echoes jarvis.context.phrase
  - Both useful for testing mic-pickup + STT-quality + TTS-clarity without
    touching LLM. If user can't hear/understand the echo, the issue is the
    audio chain, not the command logic.

Build: cargo build --release green. 99/99 tests pass.

resources/commands/intro/about.lua

@@ -0,0 +1,20 @@
+-- Short bio. Falls back to LLM if available for variation, otherwise canned text.
+local prof = jarvis.profile.active()
+local prof_part = ""
+if prof and prof.name and prof.name ~= "default" then
+    prof_part = " Сейчас работаю в режиме " .. prof.name .. "."
+end
+
+local canned = "Я Джарвис, локальный голосовой ассистент на Rust." ..
+    " Работаю на вашем компьютере, могу использовать облачный или локальный мозг." ..
+    prof_part ..
+    " Спросите 'что ты умеешь' для обзора возможностей."
+
+-- If LLM is configured, give a tiny variation. Otherwise use canned.
+local llm_text = jarvis.llm({
+    { role = "system", content = "Ты — Джарвис из вселенной Marvel, британский дворецкий Тони Старка. Одна короткая фраза (1-2 предложения) на русском, представь себя пользователю. Без слов 'я искусственный интеллект' и подобных." },
+    { role = "user", content = "Расскажи о себе одной фразой." }
+}, { max_tokens = 80, temperature = 0.8 })
+
+local msg = (llm_text and llm_text ~= "") and llm_text or canned
+return jarvis.cmd.ok(msg)