refactor(decnet_web/Config): extract types

Foundation for the Config split. UserEntry / ConfigData move out
of the page so the upcoming hook + tab extractions can import
without reaching back through Config.tsx. New ConfigTab union and
FormMsg type for the inline success/error chip pattern that
repeats across every admin form on the page.

- New Config/types.ts (UserEntry, ConfigData, ConfigTab, FormMsg)
- Config.tsx loses the inline interfaces and the `as any` cast on
  setActiveTab in the tab-switcher.

decnet_web/src/components/Config.tsx

@@ -6,25 +6,12 @@ import RuleStateControls from './RuleStateControls';
 import './Dashboard.css';
 import './Config.css';
 
-interface UserEntry {
-  uuid: string;
-  username: string;
-  role: string;
-  must_change_password: boolean;
-}
-
-interface ConfigData {
-  role: string;
-  deployment_limit: number;
-  global_mutation_interval: string;
-  users?: UserEntry[];
-  developer_mode?: boolean;
-}
+import type { ConfigData, ConfigTab } from './Config/types';
 
 const Config: React.FC = () => {
   const [config, setConfig] = useState<ConfigData | null>(null);
   const [loading, setLoading] = useState(true);
-  const [activeTab, setActiveTab] = useState<'limits' | 'users' | 'globals' | 'appearance' | 'workers' | 'ttp'>('limits');
+  const [activeTab, setActiveTab] = useState<ConfigTab>('limits');
   const [accent, setAccent] = useState<'matrix' | 'violet'>(() => {
     try {
       const raw = localStorage.getItem('decnet_tweaks');
@@ -256,7 +243,7 @@ const Config: React.FC = () => {
           <button
             key={tab.key}
             className={`config-tab ${activeTab === tab.key ? 'active' : ''}`}
-            onClick={() => setActiveTab(tab.key as any)}
+            onClick={() => setActiveTab(tab.key as ConfigTab)}
           >
             {tab.icon}
             {tab.label}

decnet_web/src/components/Config/types.ts

@@ -0,0 +1,27 @@
+/** Wire + UI types for the Config page surface. */
+
+export interface UserEntry {
+  uuid: string;
+  username: string;
+  role: string;
+  must_change_password: boolean;
+}
+
+export interface ConfigData {
+  role: string;
+  deployment_limit: number;
+  global_mutation_interval: string;
+  users?: UserEntry[];
+  developer_mode?: boolean;
+}
+
+/** Inline success/error chip surfaced under each form section. */
+export type FormMsg = { type: 'success' | 'error'; text: string };
+
+export type ConfigTab =
+  | 'limits'
+  | 'users'
+  | 'globals'
+  | 'appearance'
+  | 'workers'
+  | 'ttp';