refactor(api): split monolithic handlers.go into focused modules

Break down the 627-line handlers.go into specialized modules:
- handlers_chat.go: chat and streaming endpoints
- handlers_config.go: configuration endpoints
- handlers_common.go: shared utilities
- handlers_info.go: info and status endpoints
- handlers_terminal.go: terminal/shell endpoints
- handlers_tools.go: tool-related endpoints

Also includes config improvements, orchestrator enhancements, and
web component updates.

💘 Generated with Crush

Assisted-by: MiniMax-M2.7 via Crush <crush@charm.land>

web/src/api/client.js

@@ -2,8 +2,8 @@ const API_BASE = '/api'
 
 async function request(path, options = {}) {
   const res = await fetch(`${API_BASE}${path}`, {
-    headers: { 'Content-Type': 'application/json' },
     ...options,
+    headers: { 'Content-Type': 'application/json', ...(options.headers || {}) },
   })
   if (!res.ok) {
     const err = await res.json().catch(() => ({ error: res.statusText }))
@@ -34,9 +34,11 @@ const api = {
   getTerminalSessions: () => request('/terminal/sessions'),
   addSSHConnection: (conn) => request('/terminal/sessions', { method: 'POST', body: JSON.stringify(conn) }),
   deleteSSHConnection: (name) => request(`/terminal/sessions/${encodeURIComponent(name)}`, { method: 'DELETE' }),
+  getTerminalThemes: () => request('/terminal/themes'),
+  saveTerminalSettings: (settings) => request('/terminal/settings', { method: 'PUT', body: JSON.stringify(settings) }),
   getChatHistory: () => request('/chat/history'),
   clearChat: () => request('/chat/clear', { method: 'POST' }),
-  sendChat: (message, stream = true) => {
+  sendChat: (message, stream = true, onChunk) => {
     if (!stream) {
       return request('/chat', { method: 'POST', body: JSON.stringify({ message, stream: false }) })
     }
@@ -64,7 +66,10 @@ const api = {
               const data = JSON.parse(line.slice(6))
               if (data.error) { reject(new Error(data.error)); return }
               if (data.done) { resolve(full); return }
-              if (data.content) full += data.content
+              if (data.content) {
+                full += data.content
+                if (onChunk) onChunk(full)
+              }
             } catch {}
           }
         }