Fix: Add prompt text to the form in the MCP module (#9222)

### What problem does this PR solve?

Fix: Add prompt text to the form in the MCP module #3221

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

web/src/locales/en.ts

       nextPage: 'Next',
       add: 'Add',
       promptPlaceholder: `Please input or use / to quickly insert variables.`,
+      mcp: {
+        namePlaceholder: 'My MCP Server',
+        nameRequired:
+          'It must be 1–64 characters long and can only contain letters, numbers, hyphens, and underscores.',
+        urlPlaceholder: 'https://api.example.com/v1/mcp',
+        tokenPlaceholder: 'e.g. eyJhbGciOiJIUzI1Ni...',
+      },
     },
     login: {
       login: 'Sign in',

web/src/pages/profile-setting/mcp/edit-mcp-form.tsx

     name: z
       .string()
       .min(1, {
-        message: t('common.namePlaceholder'),
+        message: t('common.mcp.namePlaceholder'),
+      })
+      .regex(/^[a-zA-Z0-9_-]{1,64}$/, {
+        message: t('common.mcp.nameRequired'),
       })
       .trim(),
     url: z
       .string()
       .url()
       .min(1, {
-        message: t('common.namePlaceholder'),
+        message: t('common.mcp.urlPlaceholder'),
       })
       .trim(),
     server_type: z
       .string()
       .min(1, {
-        message: t('common.namePlaceholder'),
+        message: t('common.pleaseSelect'),
       })
       .trim(),
     authorization_token: z.string().optional(),
               <FormLabel>{t('common.name')}</FormLabel>
               <FormControl>
                 <Input
-                  placeholder={t('common.namePlaceholder')}
+                  placeholder={t('common.mcp.namePlaceholder')}
                   {...field}
                   autoComplete="off"
                 />
               <FormLabel>{t('mcp.url')}</FormLabel>
               <FormControl>
                 <Input
-                  placeholder={t('common.namePlaceholder')}
+                  placeholder={t('common.mcp.urlPlaceholder')}
                   {...field}
                   autoComplete="off"
                   onChange={(e) => {
               <FormLabel>Authorization Token</FormLabel>
               <FormControl>
                 <Input
-                  placeholder={t('common.namePlaceholder')}
+                  placeholder={t('common.mcp.tokenPlaceholder')}
                   {...field}
                   autoComplete="off"
                   type="password"