feat: add model-aware DSH image input

DeepSeek Harness previously treated every selected model as text-only. It now carries the model profile's image capability through Main, the Utility Host, ACP, and Pi-AI, rejects unsupported images before model invocation, and validates supported JPEG/PNG data in a bounded process-local attachment store.

The Composer keeps universal controls on its first row, places OpenCode and Continue controls on a dedicated responsive row, and anchors context compaction without shifting the footer. Runtime supervision ownership for future Subagents and Jobs is documented for the right sidebar.

Release note: DeepSeek Harness 现可按所选模型连接的能力安全接收 JPEG/PNG 图片；Composer 同时将 Runtime 专属选择器移到独立一行，并固定上下文压缩入口。

src/main/agent/deepseek-harness-control-protocol.ts

@@ -8,10 +8,12 @@ import {
 
 export const DEEPSEEK_HARNESS_CONTROL_PROTOCOL =
   'goodbuddy.deepseek-harness.control'
-export const DEEPSEEK_HARNESS_CONTROL_VERSION = 1
+export const DEEPSEEK_HARNESS_CONTROL_VERSION = 2
 export const DEEPSEEK_HARNESS_HOST_VERSION = '0.1.0-rc.6'
 export const DEEPSEEK_HARNESS_CREDENTIAL_REF =
   'GOODBUDDY_HARNESS_MODEL_API_KEY'
+export const DEEPSEEK_HARNESS_MAX_FRAME_BYTES =
+  8 * 1024 * 1024
 
 const skillPackageSchema = z
   .object({
@@ -43,13 +45,14 @@ export const controlledHarnessHostConfigSchema = z
     api: z.literal('openai-completions'),
     provider: z.literal('goodbuddy'),
     model: z.string().min(1).max(128),
+    supportsImageInput: z.boolean(),
     harnessVersion: z.literal(DEEPSEEK_HARNESS_HOST_VERSION),
     credentialRefs: z
       .tuple([z.literal(DEEPSEEK_HARNESS_CREDENTIAL_REF)])
       .readonly(),
     skillPackages: z.array(skillPackageSchema).max(64),
     extensionPackages: z.array(extensionPackageSchema).max(64),
-    maxFrameBytes: z.literal(1024 * 1024)
+    maxFrameBytes: z.literal(DEEPSEEK_HARNESS_MAX_FRAME_BYTES)
   })
   .strict()