Add HeXi bot codebase: custom plugins, web frontends, tests

- hexi core: message handling, rate limiting, cooldown, plugin manager
- Custom plugins: BF stats, daily check-in, quotes, persona cards, etc.
- Community plugins vendored under hexi/plugins with local fixes
- Web admin frontends (learning-chat, persona-admin), unified hexi/web
- Tests for rate_limit/cooldown/memes/persona; poetry.lock

Co-Authored-By: Claude <noreply@anthropic.com>

hexi/plugins/nonebot_plugin_picstatus/collectors/mem.py

@@ -0,0 +1,30 @@
+from dataclasses import dataclass
+
+import psutil
+
+from . import normal_collector, periodic_collector
+
+
+@dataclass
+class MemoryStat:
+    percent: float
+    used: int
+    total: int
+
+
+async def get_memory_stat() -> MemoryStat:
+    mem = psutil.virtual_memory()
+    return MemoryStat(percent=mem.percent, used=mem.used, total=mem.total)
+
+
+normal_collector("memory_stat")(get_memory_stat)
+periodic_collector("memory_stat_periodic")(get_memory_stat)
+
+
+async def get_swap_stat() -> MemoryStat:
+    swap = psutil.swap_memory()
+    return MemoryStat(percent=swap.percent, used=swap.used, total=swap.total)
+
+
+normal_collector("swap_stat")(get_swap_stat)
+periodic_collector("swap_stat_periodic")(get_swap_stat)