fix(apiproxy): configure session export compression

Session-log ZIP entries always used DEFLATE level 6 even though compression level is a deployment tradeoff: CPU-constrained hosts may prefer low latency while bandwidth-constrained hosts may prefer smaller archives. A hardcoded level also violated the repository rule that deployment-varying plugin choices live in validated Config.

Add sessionExportCompressionLevel to ApiProxyService.Config as an integer 0-9 with default 6, resolve the same default once for direct createApiProxy callers, and pass the required level into the streaming module. Tests prove schema defaulting and rejection as well as a level-0 versus level-9 archive-size difference with identical extracted content. The generated config catalog, bilingual gateway README, and feature note document the knob and its tradeoff.

packages/host/apiproxy/src/api-proxy.ts

@@ -43,11 +43,13 @@ import type {
   WorkspaceId, WorkspaceView,
 } from './api/index.ts'
 import {
+  DEFAULT_SESSION_LOG_COMPRESSION_LEVEL,
   flushLiveSessionLog,
   sessionLogExportDeps,
   sessionLogZipFilename,
   streamSessionLogZip,
   type SessionLogExportReady,
+  type SessionLogCompressionLevel,
 } from './session-export.ts'
 import type { SessionRawArtifact } from '@deepseek-ai/dsh-session-persistence'
 import {
@@ -544,6 +546,8 @@ export interface ApiProxyDefaults {
   openPath?: (path: string, signal: AbortSignal) => Promise<void>
   /** Native text-editor handoff; injectable for settings-document tests. */
   openTextFile?: (path: string, signal: AbortSignal) => Promise<void>
+  /** Validated DEFLATE level for session-log ZIP entries; defaults to 6. */
+  sessionExportCompressionLevel?: SessionLogCompressionLevel
   /**
    * Whether handing a path to the native opener can work at all — the
    * `hasDocument` capability the preset roster reports, and the switch
@@ -989,6 +993,8 @@ function changedWorkspaceView(workspaceId: string, value: unknown): WorkspaceVie
  * @returns the ApiProxy implementation.
  */
 export function createApiProxy(ctx: Context, defaults: ApiProxyDefaults): ApiProxy {
+  const sessionExportCompressionLevel = defaults.sessionExportCompressionLevel
+    ?? DEFAULT_SESSION_LOG_COMPRESSION_LEVEL
   /** The seed model each create/resume declares; re-read so it never goes stale. */
   const agentOptions = (): AgentOptions => {
     const { provider, model } = defaults.defaultModelSelection()
@@ -3517,7 +3523,14 @@ export function createApiProxy(ctx: Context, defaults: ApiProxyDefaults): ApiPro
           return new Response('session not found', { status: 404 })
         }
         return new Response(
-          streamSessionLogZip(ready, root, request.sessionId, request.includeDescendants === true, signal),
+          streamSessionLogZip(
+            ready,
+            root,
+            request.sessionId,
+            request.includeDescendants === true,
+            sessionExportCompressionLevel,
+            signal,
+          ),
           {
             headers: {
               'content-type': 'application/zip',