feat: customize model provider requests

Model connections can now save bounded JSON request headers and top-level body fields. Direct requests and Continue support both; local OpenCode and DeepSeek Harness use only native header support, while the managed remote OpenCode gateway applies both.

Runtime, protocol, and authentication fields keep precedence. Custom values are ordinary connection settings, not credential storage. This migrates Runtime settings from v20 to v21 and updates the DeepSeek control and managed Runtime ACP capabilities.

Release note: 模型连接详情新增自定义请求头和请求体；直连与 Continue 支持两者，本地 OpenCode 和 DeepSeek Harness 仅应用原生支持的请求头，受管远程 OpenCode 支持两者，界面会明确提示生效范围。

src/main/agent/runtime-e2e.manual.test.ts

@@ -36,6 +36,12 @@ import {
 } from '../../shared/goodbuddy-config-tools'
 import { KnowledgeMcpGateway } from './knowledge-mcp-gateway'
 import { SubagentScheduler } from '../assistant/subagent-scheduler'
+import { createAnthropicMessagesUrl } from './anthropic-endpoint'
+import {
+  createOpenAIChatCompletionsUrl,
+  createOpenAIResponsesUrl
+} from './openai-endpoint'
+import { createModelRequestProbe } from '../../../tests/support/model-request-probe'
 
 const enabled = process.env.GOODBUDDY_RUN_RUNTIME_E2E === '1'
 const apiKey =
@@ -374,6 +380,65 @@ describe.runIf(enabled)('runtime end-to-end', () => {
     120_000
   )
 
+  it(
+    'adds configured headers and body fields to one real direct model request',
+    async () => {
+      const upstreamUrl =
+        protocol === 'anthropic-messages'
+          ? createAnthropicMessagesUrl(baseUrl)
+          : protocol === 'openai-responses'
+            ? createOpenAIResponsesUrl(baseUrl)
+            : createOpenAIChatCompletionsUrl(baseUrl)
+      const probe = await createModelRequestProbe({
+        upstreamUrl,
+        headerName: 'x-goodbuddy-e2e',
+        bodyFieldNames: ['goodbuddy_e2e_probe'],
+        removeBodyFieldNames: ['goodbuddy_e2e_probe']
+      })
+      const runtime = new ModelAgentRuntime({
+        apiKey,
+        baseUrl: probe.baseUrl,
+        model: modelName,
+        protocol,
+        authentication: 'api-key',
+        requestHeaders: {
+          'x-goodbuddy-e2e': 'header-present'
+        },
+        requestBody: {
+          goodbuddy_e2e_probe: 'body-present'
+        }
+      })
+
+      try {
+        const output = await collectText(
+          runtime.run(
+            {
+              requestId: crypto.randomUUID(),
+              conversationId: crypto.randomUUID(),
+              workMode: 'ask',
+              prompt:
+                'Return exactly this text and nothing else: CUSTOM_REQUEST_E2E_OK'
+            },
+            new AbortController().signal
+          )
+        )
+        expect(output).toContain('CUSTOM_REQUEST_E2E_OK')
+        expect(probe.observations).toEqual([
+          {
+            headerValue: 'header-present',
+            bodyFields: {
+              goodbuddy_e2e_probe: 'body-present'
+            }
+          }
+        ])
+      } finally {
+        await runtime.dispose()
+        await probe.close()
+      }
+    },
+    180_000
+  )
+
   it(
     'uses real direct-model process execution and a programming Subagent to repair and verify code',
     async () => {