refactor(cli): parse dsh argv through one Commander adapter

Replace the dsh CLI's three hand-rolled parsing idioms (raw argv[0]/includes
dispatch in bin.ts, per-mode node:util parseArgs in headless.ts/web.ts, and the
bespoke parseResumeArg scanner in dsh-app-boot) with a single Commander adapter
in apps/cli/src/args.ts. parseDshArgs resolves argv into a discriminated
DshInvocation union; bin.ts switches on the mode and dynamic-imports the chosen
module, which now consumes already-parsed values.

- web is a real subcommand; --host uses choices and --port an argParser range
  check, moving validation into the parser.
- --resume rejects empty and repeated forms; --prompt rejects empty; a config
  positional after --prompt and a root flag placed before web fail loud.
- adds --help/--version; removes parseResumeArg from dsh-app-boot.
- new apps/cli/tests/args.spec.ts (apps/*/tests added to vitest include,
  apps/cli/tests to tsconfig.host.json); the tui-agent keyless PTY smoke covers
  bin.ts dispatch end to end unchanged.

apps/cli/src/bin.ts

@@ -1,25 +1,58 @@
 #!/usr/bin/env node
 /**
- * dsh — command-line entry. Coarse dispatch only; each surface module owns its
- * argument handling. Dynamic imports keep unrelated surfaces out of each
- * dispatch path; everything except `web` and headless prompts opens the TUI.
+ * dsh — command-line entry. Parses argv once through the Commander adapter and
+ * switches on the resolved mode; dynamic imports keep unrelated modes out of
+ * each dispatch path. `web` and headless prompts run their own module;
+ * everything else opens the TUI. `--help`/`--version` print and exit 0; a parse
+ * error prints to stderr and exits 1.
  * @module @deepseek-ai/dsh/bin
  */
 
 /* v8 ignore file -- built-bin and PTY tests exercise this self-executing dispatch. */
 
+import { readFileSync } from 'node:fs'
+import { fileURLToPath } from 'node:url'
 import { loadEnv } from '@deepseek-ai/dsh-app-boot'
+import { parseDshArgs } from './args.ts'
+
+// Both the source tree (apps/cli/src) and the bundled bin (apps/cli/lib) sit
+// one directory under apps/cli, so the checked-in manifest resolves with the
+// same relative hop from either artifact.
+/** This app's version, read from its checked-in package.json. */
+function readVersion(): string {
+  const manifest = JSON.parse(
+    readFileSync(fileURLToPath(new URL('../package.json', import.meta.url)), 'utf8'),
+  ) as { version?: unknown }
+  return typeof manifest.version === 'string' ? manifest.version : '0.0.0'
+}
 
 loadEnv('dsh')
-const argv = process.argv.slice(2)
+const invocation = parseDshArgs(process.argv.slice(2), readVersion())
 
-if (argv[0] === 'web') {
-  const { runWeb } = await import('./web.ts')
-  await runWeb(argv.slice(1))
-} else if (argv.includes('-p') || argv.includes('--prompt')) {
-  const { runHeadless } = await import('./headless.ts')
-  await runHeadless(argv)
-} else {
-  const { runTui } = await import('./tui.ts')
-  await runTui(argv)
+switch (invocation.mode) {
+  case 'web': {
+    const { runWeb } = await import('./web.ts')
+    await runWeb(invocation.host, invocation.port)
+    break
+  }
+  case 'headless': {
+    const { runHeadless } = await import('./headless.ts')
+    await runHeadless(invocation.prompt)
+    break
+  }
+  case 'tui': {
+    const { runTui } = await import('./tui.ts')
+    await runTui(invocation.config, invocation.resume)
+    break
+  }
+  case 'help':
+  case 'version':
+    process.stdout.write(invocation.text)
+    process.exit(0)
+  case 'error':
+    process.stderr.write(`${invocation.message}\n`)
+    process.exit(1)
+  default:
+    invocation satisfies never
+    throw new Error(`dsh: unhandled invocation mode ${JSON.stringify(invocation)}`)
 }