Select OpenCode plugin exports from the execution host version (#24662)

* fix: wait for OpenCode worker composer before first dispatch

Reuse captured composer readiness on local and paired execution hosts and revoke launching-shell paste anchors.

Co-authored-by: Brennan Benson <79079362+brennanb2025@users.noreply.github.com>

* feat(opencode): probe execution-host CLI capabilities

* fix(opencode): select plugin default for execution host loader

* fix(opencode): limit prompt prefill capability to verified release

* feat(opencode): probe launch capabilities on the execution host

* fix(opencode): select plugin loader for the launched host binary

* fix(opencode): match WSL probe cwd and declared guest environment

* fix(opencode): preserve launch environment deletion boundaries

* STRICT launch CI contract correction

* CAPS launch CI contract correction

* test: initialize Claude prompt state in output retention fixture

---------

Co-authored-by: Brennan Benson <79079362+brennanb2025@users.noreply.github.com>

src/shared/opencode-cli-version.ts

@@ -0,0 +1,26 @@
+import { isValidAppVersion } from './app-version'
+
+export type OpenCodeCliCapabilities = {
+  version: string | null
+  pluginApi: 'v1' | 'v2' | 'unknown'
+  promptMode: 'submit' | 'prefill' | 'unknown'
+}
+
+export function parseOpenCodeCliVersion(output: string | null | undefined): string | null {
+  const version = output
+    ?.trim()
+    .match(/^(?:opencode\s+)?v?(\d+\.\d+\.\d+(?:-[0-9A-Za-z.-]+)?(?:\+[0-9A-Za-z.-]+)?)$/i)?.[1]
+  return version && isValidAppVersion(version) ? version : null
+}
+
+export function getOpenCodeCliCapabilities(
+  output: string | null | undefined
+): OpenCodeCliCapabilities {
+  const version = parseOpenCodeCliVersion(output)
+  const major = version?.split('.')[0]
+  return {
+    version,
+    pluginApi: major === '1' ? 'v1' : major === '2' ? 'v2' : 'unknown',
+    promptMode: major === '1' ? 'submit' : version === '2.0.16' ? 'prefill' : 'unknown'
+  }
+}