feat: add PUT /api/0/users/me for user self-service profile updates

Allows any authenticated user to update their own full_name, avatar,
notification_channels, and password via the config YAML write path.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

hbd/server/http.py

@@ -1173,6 +1173,62 @@ async def start(
 
         return web.json_response({"ok": True})
 
+    async def api_user_self_put(request):
+        """PUT /api/0/users/me — update own full_name, avatar, notification_channels, password."""
+        user, err = _require_auth(request)
+        if err:
+            return err
+        if user is None:
+            return web.json_response({"error": "Authentication required"}, status=401)
+        if not _config_path:
+            return web.json_response({"error": "Config path not available"}, status=503)
+
+        try:
+            body = await request.json()
+        except Exception:
+            return web.json_response({"error": "Invalid JSON"}, status=400)
+
+        if not isinstance(body, dict):
+            return web.json_response({"error": "Invalid JSON"}, status=400)
+
+        username = user.username
+        password_change = body.get("password")
+
+        if password_change:
+            current_pw = password_change.get("current", "")
+            new_pw = password_change.get("new", "")
+            if not new_pw:
+                return web.json_response({"error": "New password cannot be empty"}, status=400)
+            if not users_mod.authenticate(username, current_pw):
+                return web.json_response({"error": "Current password incorrect"}, status=403)
+
+        try:
+            data = configio_mod.read_roundtrip(_config_path)
+            if "users" not in data or data["users"] is None:
+                data["users"] = {}
+            user_entry = dict(data["users"].get(username) or {})
+
+            if "full_name" in body:
+                user_entry["full_name"] = str(body["full_name"])
+            if "avatar" in body:
+                user_entry["avatar"] = str(body["avatar"])
+            if "notification_channels" in body:
+                user_entry["notification_channels"] = list(body["notification_channels"])
+            if password_change:
+                user_entry["password"] = users_mod.hash_password(password_change["new"])
+
+            data["users"][username] = user_entry
+            configio_mod.write_config(_config_path, data)
+        except Exception as exc:
+            logger.error("User self-update failed: %s", exc)
+            return web.json_response({"error": str(exc)}, status=500)
+
+        if hasattr(config, "reload"):
+            await config.reload()
+        users_mod.load_users(config)
+
+        return web.json_response({"ok": True})
+
     app = web.Application()
     app.add_routes(
         [
@@ -1189,6 +1245,7 @@ async def start(
             # Users
             web.get("/api/0/users", api_users),
             web.get("/api/0/users/me", api_user_self),
+            web.put("/api/0/users/me",  api_user_self_put),
             web.get("/api/0/users/{username}/avatar", api_user_avatar),
             # Config API (admin)
             web.get("/api/0/config",                 api_config_get),