feat: unit conversion + random generators packs (7 new commands)

Two pure-Lua packs that don't need network or LLM — pure offline utilities.

unit_convert (resources/commands/unit_convert/, 4 commands)
  - convert.length      "переведи 100 метров в футы" / "сколько 5 миль в км"
                        meters↔feet, km↔miles. Pluralises russian unit names.
  - convert.weight      "переведи 70 кг в фунты"
                        kg↔lbs.
  - convert.temperature "переведи 100 цельсий в фаренгейт" / "минус 40 в цельсий"
                        Handles negative numbers. C↔F formulas inline.
  - convert.speed       "переведи 100 км в час в мили в час"
                        km/h↔mph.
  - All round results to 1-2 decimal places, speak with proper Russian
    grammatical number (фут/фута/футов).

generators (resources/commands/generators/, 3 commands)
  - gen.coin       "подбрось монету" / "орёл или решка"
                   → "Орёл!" or "Решка!" (math.random with time+minute seed)
  - gen.password   "сгенерируй пароль 16 символов"
                   → cryptographically-ish 6..64-char password,
                   alphanumeric + !@#$%^&*-_=+, copies to clipboard,
                   SPEAKS LENGTH ONLY (never echoes the password).
                   Default 16 chars if no number in phrase.
  - gen.uuid       "сгенерируй uuid" / "юид"
                   → v4 UUID, copies to clipboard, speaks last 4 chars
                   (confirmation without 32-char monologue).

Tests: 112/112 pass (commands::tests auto-validates).
Pack count: 62 → 64.

resources/commands/generators/coin.lua

@@ -0,0 +1,6 @@
+math.randomseed(os.time() + (jarvis.context.time.minute or 0) * 1000)
+local r = math.random(1, 2)
+if r == 1 then
+    return jarvis.cmd.ok("Орёл!")
+end
+return jarvis.cmd.ok("Решка!")