feat(plugins): implement plugin loading and management system

- Added PluginLoader component to dynamically load and initialize plugins.
- Created Plugins component for managing installed and marketplace plugins.
- Introduced PluginAPI for plugin interaction and settings management.
- Defined types for plugin metadata, installed plugins, and plugin index.
- Implemented settings rendering for plugins based on their schema.
- Integrated marketplace plugin fetching and installation logic.
- Added support for enabling/disabling and uninstalling plugins.

src/app/features/room/RoomInput.tsx

@@ -102,6 +102,7 @@ import {
 import { getMemberDisplayName, getMentionContent, trimReplyFromBody } from '../../utils/room';
 import { CommandAutocomplete } from './CommandAutocomplete';
 import { Command, SHRUG, TABLEFLIP, UNFLIP, useCommands } from '../../hooks/useCommands';
+import { pluginRegistry } from '../settings/plugins/PluginAPI';
 import { mobileOrTablet } from '../../utils/user-agent';
 import { useElementSizeObserver } from '../../hooks/useElementSizeObserver';
 import { ReplyLayout, ThreadIndicator } from '../../components/message';
@@ -308,7 +309,7 @@ export const RoomInput = forwardRef<HTMLDivElement, RoomInputProps>(
       contents.forEach((content) => mx.sendMessage(roomId, content as any));
     };
 
-    const submit = useCallback(() => {
+    const submit = useCallback(async () => {
       uploadBoardHandlers.current?.handleSend();
 
       const commandName = getBeginCommand(editor);
@@ -340,9 +341,30 @@ export const RoomInput = forwardRef<HTMLDivElement, RoomInputProps>(
         plainText = `${UNFLIP} ${plainText}`;
         customHtml = `${UNFLIP} ${customHtml}`;
       } else if (commandName) {
+        // Check built-in commands first
         const commandContent = commands[commandName as Command];
         if (commandContent) {
           commandContent.exe(plainText);
+          resetEditor(editor);
+          resetEditorHistory(editor);
+          sendTypingStatus(false);
+          return;
+        }
+
+        // Check plugin commands
+        try {
+          const result = await pluginRegistry.executeCommand(commandName, plainText);
+          if (result) {
+            // If command returns text, send it as a message
+            const content: IContent = {
+              msgtype: MsgType.Text,
+              body: result,
+            };
+            mx.sendMessage(roomId, content as any);
+          }
+        } catch (err) {
+          console.error(`[RoomInput] Plugin command /${commandName} failed:`, err);
+          // Show error to user (could integrate with notification system)
         }
         resetEditor(editor);
         resetEditorHistory(editor);
@@ -398,6 +420,27 @@ export const RoomInput = forwardRef<HTMLDivElement, RoomInputProps>(
           'm.in_reply_to': { event_id: threadRootId },
         };
       }
+      
+      // Process message through plugin interceptors
+      try {
+        const messageContext = {
+          content: content.body,
+          roomId,
+          eventType: 'm.room.message',
+          formatted: content.formatted_body,
+          metadata: {},
+        };
+        const processedContext = await pluginRegistry.processBeforeSend(messageContext);
+        
+        // Update content with intercepted values
+        content.body = processedContext.content;
+        if (processedContext.formatted) {
+          content.formatted_body = processedContext.formatted;
+        }
+      } catch (err) {
+        console.error('[RoomInput] Plugin interceptor error:', err);
+      }
+      
       mx.sendMessage(roomId, content as any);
       resetEditor(editor);
       resetEditorHistory(editor);