refactor(cli): bail early in the arg adapter instead of returning errors as data

Address review and cut ceremony: the adapter no longer models help/version/
errors as DshInvocation members. Commander owns those under exitOverride — it
prints usage or the diagnostic and one try/catch in parseDshArgs turns the
thrown CommanderError into process.exit with the intended code. bin.ts drops its
help/version/error cases; the union is the three real modes.

Domain checks bail via command.error(print + exit 1): --prompt rejects an empty
task or a stray config/--resume, empty --resume= fails loud, and --host/--port
are validated. A repeated --resume or a flag captured as a value is Commander's
standard behavior, left alone (a bad id fails loud downstream). dsh --help
discloses web via addHelpText. Net: args.ts 185 -> 112 lines.

Also fixes review nits: built-bin e2e resolves on `close`; the /resume handoff
uses `dsh --resume=<id> -- <config>` so a config named `web` stays a positional;
and stale prose (cordis.yml comment, app-boot module doc + duplicate JSDoc,
ui/README, two feature notes, an agent-loop test name) tracks the shipped state.
Removes tui-demo's now-dead plugin-include dep and vendor/loader + app-boot
tsconfig references.

examples/tui-agent/cordis.yml

@@ -34,8 +34,8 @@
     model: deepseek-v4-pro
     # `dsh --resume <id>` provides the session id on the boot context (the ids
     # live under ./.sessions); with no flag the identifier is undefined and a
-    # fresh session starts each run. The demo bin never provides it, so the
-    # typeof guard reads undefined there rather than throwing.
+    # fresh session starts each run. The typeof guard tolerates a launcher that
+    # never provides the slot, reading undefined rather than throwing.
     resumeSessionId: !!js "typeof resumeSessionId === 'string' ? resumeSessionId : undefined"
     persistenceRoot: './.sessions'
     # Printed on exit and listed by `/resume`; `{session}` fills the live id.