feat: add ui.seamColor accent

src/config/config.ts

@@ -346,6 +346,10 @@ export type ClawdisConfig = {
   };
   logging?: LoggingConfig;
   browser?: BrowserConfig;
+  ui?: {
+    /** Accent color for Clawdis UI chrome (hex). */
+    seamColor?: string;
+  };
   skillsLoad?: SkillsLoadConfig;
   skillsInstall?: SkillsInstallConfig;
   models?: ModelsConfig;
@@ -494,6 +498,10 @@ const TranscribeAudioSchema = z
   })
   .optional();
 
+const HexColorSchema = z
+  .string()
+  .regex(/^#?[0-9a-fA-F]{6}$/, "expected hex color (RRGGBB)");
+
 const SessionSchema = z
   .object({
     scope: z.union([z.literal("per-sender"), z.literal("global")]).optional(),
@@ -672,6 +680,11 @@ const ClawdisSchema = z.object({
       attachOnly: z.boolean().optional(),
     })
     .optional(),
+  ui: z
+    .object({
+      seamColor: HexColorSchema.optional(),
+    })
+    .optional(),
   models: ModelsConfigSchema,
   agent: z
     .object({