fix: keep valid older agent packages usable after desktop updates

Accept package-declared OpenCode, Node and koffi versions instead of desktop release pins. Preserve signature, hash, protocol and package-internal version consistency checks.

Validate both cached 0.11.18 packages and Linux x64 installation, bootstrap, health and stop. Related regression suite: 326 passed, 1 skipped; unrelated full-workspace check failures are recorded in the remote Host design.

Release note: Desktop updates no longer reject intact older Agent packages solely because their bundled runtime versions differ.

src/shared/remote-runtime-launch-contracts.ts

@@ -5,7 +5,8 @@ import {
   agentManifestLicenseSchema,
   agentManifestPathSchema,
   agentProtocolVersionSchema,
-  agentReleaseKeySchema
+  agentReleaseKeySchema,
+  componentVersionSchema
 } from './agent-installation-contracts'
 import {
   agentIdentifierSchema,
@@ -227,7 +228,8 @@ export const remoteRuntimeLockSchema = z
       .object({
         opencode: z
           .object({
-            version: z.literal('1.18.29'),
+            // Installed packages carry their own signed Runtime version.
+            version: componentVersionSchema,
             provider: z.literal('opencode'),
             entrypoint: z.literal('bin/opencode'),
             entrypointIdentity: z.literal('opencode-acp'),