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/agent-installation-contracts.ts

@@ -239,7 +239,7 @@ export const agentRuntimeLockSchema = z
     protocol: agentProtocolVersionSchema,
     node: z
       .object({
-        version: z.literal('24.19.0'),
+        version: componentVersionSchema,
         source: z
           .url()
           .refine(
@@ -257,7 +257,7 @@ export const agentRuntimeLockSchema = z
       .strict(),
     koffi: z
       .object({
-        version: z.literal('3.1.4')
+        version: componentVersionSchema
       })
       .strict()
   })