feat(ticket): rewrite ticket system from scratch inspired by Kuby

New minimal ticket system (dev only):
- Panel with create ticket button (Components V2, no accent colors)
- Category selection via dropdown or direct modal (1 cat)
- Ticket channel creation with permissions, staff role, welcome message
- Close flow: staff check, transcript HTML (dark theme), log, auto-delete
- /ticket setup, /ticket config (interactive panel)
- Storage: JSON per-ticket + config.json (singleton pattern)
- Modular architecture: data.py, storage.py, ui.py, transcript.py, cog.py
- Removed old modmail system

tickets/storage.py

@@ -0,0 +1,86 @@
+from __future__ import annotations
+
+import json
+import logging
+import threading
+
+from config import DATA_DIR
+from tickets.data import GuildTicketConfig, TicketData
+
+logger = logging.getLogger("vision")
+
+TICKETS_DIR = DATA_DIR / "tickets"
+_CONFIG_FILE = TICKETS_DIR / "config.json"
+
+_lock = threading.Lock()
+_config_cache: dict[int, GuildTicketConfig] = {}
+_tickets_cache: dict[int, TicketData] = {}
+
+
+def _ensure_dirs():
+    TICKETS_DIR.mkdir(parents=True, exist_ok=True)
+
+
+def _load_all_configs() -> dict[int, GuildTicketConfig]:
+    global _config_cache
+    _ensure_dirs()
+    if _config_cache:
+        return _config_cache
+    if _CONFIG_FILE.exists():
+        with open(_CONFIG_FILE, "r", encoding="utf-8") as f:
+            raw = json.load(f)
+        _config_cache = {int(k): GuildTicketConfig.from_dict(v) for k, v in raw.items()}
+    else:
+        _config_cache = {}
+    return _config_cache
+
+
+def _save_all_configs():
+    _ensure_dirs()
+    data = {str(k): v.to_dict() for k, v in _config_cache.items()}
+    with open(_CONFIG_FILE, "w", encoding="utf-8") as f:
+        json.dump(data, f, indent=2, ensure_ascii=False)
+
+
+def get_config(guild_id: int) -> GuildTicketConfig:
+    with _lock:
+        configs = _load_all_configs()
+        if guild_id not in configs:
+            configs[guild_id] = GuildTicketConfig(guild_id=guild_id)
+        return configs[guild_id]
+
+
+def save_config(config: GuildTicketConfig):
+    with _lock:
+        _config_cache[config.guild_id] = config
+        _save_all_configs()
+
+
+def get_ticket(channel_id: int) -> TicketData | None:
+    with _lock:
+        if channel_id in _tickets_cache:
+            return _tickets_cache[channel_id]
+        ticket_file = TICKETS_DIR / f"{channel_id}.json"
+        if ticket_file.exists():
+            with open(ticket_file, "r", encoding="utf-8") as f:
+                ticket = TicketData.from_dict(json.load(f))
+            _tickets_cache[channel_id] = ticket
+            return ticket
+    return None
+
+
+def save_ticket(ticket: TicketData):
+    with _lock:
+        _tickets_cache[ticket.channel_id] = ticket
+        _ensure_dirs()
+        ticket_file = TICKETS_DIR / f"{ticket.channel_id}.json"
+        with open(ticket_file, "w", encoding="utf-8") as f:
+            json.dump(ticket.to_dict(), f, indent=2, ensure_ascii=False)
+
+
+def delete_ticket(channel_id: int):
+    with _lock:
+        _tickets_cache.pop(channel_id, None)
+        ticket_file = TICKETS_DIR / f"{channel_id}.json"
+        if ticket_file.exists():
+            ticket_file.unlink()