feat: lock_workstation + screenshot + net_info packs + modernise power pack

Three handy daily-driver packs + cleanup of the oldest power/act.lua.

power pack — added lock_workstation (resources/commands/power/)
  - New command id: lock_workstation
  - Phrase: "заблокируй компьютер" / "заблокируй пк" / "заблокируй экран"
  - Action: rundll32.exe user32.dll,LockWorkStation
  - Sandbox: full (needs system.exec)
  - act.lua modernised:
    * No more inline PowerShell SAPI escape chain — now uses jarvis.speak
      (TTS backend abstraction respects user's chosen Piper/SAPI/Silero).
    * Returns via jarvis.cmd.ok/error helpers.
    * Logged warning for failing cmds without crashing the pack.
    * Cleaner per-action `warn` flag controls the "say cancel to abort" hint.

screenshot pack (NEW, resources/commands/screenshot/, 2 commands)
  - "сделай скрин" / "сделай скриншот" → screenshot.to_clipboard
    Uses [System.Windows.Forms.Clipboard]::SetImage() with a captured Bitmap.
    No file artifact, no LLM call — pure capture, fastest path.
  - "сохрани скрин" → screenshot.to_file
    Saves to ~/Pictures/Screenshots/jarvis-YYYYMMDD-HHMMSS.png.
    Creates dir if missing. Notifies with full path.
  - Distinct from vision/ pack which captures + describes via LLM.

net_info pack (NEW, resources/commands/net_info/, 3 commands)
  - "какая сеть" / "какой wifi" → net.wifi_ssid
    Parses `netsh wlan show interfaces` for SSID line (RU + EN field names).
  - "мой IP" / "локальный IP" → net.local_ip
    PowerShell Get-NetIPAddress, filters out 127.* and 169.* (link-local).
  - "внешний IP" / "публичный IP" → net.public_ip
    Hits api.ipify.org via jarvis.http.get (no key, plain text).

Tests: 99/99 pass (commands::tests auto-validates new packs).
Build: cargo build --release -p jarvis-app green.

Pack count: 59 → 62 (intro/echo from prior commit + screenshot + net_info; power
already counted — added a command, not a pack).

resources/commands/net_info/command.toml

@@ -0,0 +1,56 @@
+# Network info — WiFi SSID, local IP, public IP via PowerShell + free service.
+# Separate from existing `network` pack which likely covers different things.
+
+[[commands]]
+id = "net.wifi_ssid"
+type = "lua"
+script = "wifi.lua"
+sandbox = "full"
+timeout = 5000
+
+[commands.phrases]
+ru = [
+    "к какой сети я подключен",
+    "какой wi-fi",
+    "какой вайфай",
+    "какая сеть",
+    "имя сети",
+]
+en = ["what wifi", "what network", "wifi name", "ssid"]
+ua = ["до якої мережі"]
+
+
+[[commands]]
+id = "net.local_ip"
+type = "lua"
+script = "local_ip.lua"
+sandbox = "full"
+timeout = 5000
+
+[commands.phrases]
+ru = [
+    "мой локальный ip",
+    "мой ip",
+    "айпи адрес",
+    "локальный адрес",
+]
+en = ["my ip", "local ip", "ip address"]
+ua = ["моя айпі", "локальна адреса"]
+
+
+[[commands]]
+id = "net.public_ip"
+type = "lua"
+script = "public_ip.lua"
+sandbox = "full"
+timeout = 10000
+
+[commands.phrases]
+ru = [
+    "мой внешний ip",
+    "публичный ip",
+    "внешний айпи",
+    "какой у меня внешний",
+]
+en = ["public ip", "external ip", "what's my ip online"]
+ua = ["зовнішня айпі"]