Refactor AI chat: streaming, tool calls, UI polish

apps/server/src/ai-config/dto/ai-config.dto.ts

@@ -42,6 +42,10 @@ export class SaveAiConfigDto {
   @IsBoolean()
   enabled?: boolean;
 
+  @IsOptional()
+  @IsBoolean()
+  supportsVision?: boolean;
+
   @IsOptional()
   @IsInt()
   @Min(1000)
@@ -85,6 +89,7 @@ export interface AiConfigResponseDto {
   keySource: 'database' | 'environment' | 'none';
   defaultModel: string | null;
   enabled: boolean;
+  supportsVision: boolean;
   timeoutMs: number;
   verified: boolean;
   lastTestedAt: string | null;
@@ -111,6 +116,7 @@ export interface AiRuntimeConfig {
   defaultModel: string;
   timeoutMs: number;
   enabled: boolean;
+  supportsVision: boolean;
 }
 
 /** DTO for POST /api/ai/config/models — fetch available model list from provider */