feat(ui): add dedicated TUI package

Move the interactive pi-tui front door into @deepseek-ai/dsh-tui while keeping @deepseek-ai/dsh-stdio line-oriented for pipes. Select the terminal package in the demo app, preserve logger ownership, and cover the production Loader composition with a PTY smoke test.

examples/coding-agent/cordis.yml

@@ -1,6 +1,6 @@
-# REPL agent with swappable DeepSeek and local-bash backends. `dsh-stdio-demo`
-# supplies the agent spine, generic task controls, logging, JSONL persistence,
-# readline UI, and `main` agent.
+# Coding agent with swappable DeepSeek and local-bash backends. `dsh-stdio-demo`
+# supplies the agent spine, generic task controls, JSONL persistence, TTY-selected
+# `dsh-tui`/`dsh-stdio` terminal front doors, and `main` agent.
 # HMR remains a leaf because it requires Loader internals; `demo:repl` passes
 # `--expose-internals`. The app bin loads the gitignored root `.env`; this file
 # reads `DEEPSEEK_API_KEY` and optional `DEEPSEEK_BASE_URL` through `!!js`.
@@ -38,6 +38,11 @@
     resumeSessionId: !!js process.env.RESUME_SESSION_ID
     persistenceRoot: './.sessions'
     welcome: 'agent REPL ready. Give it a coding task.'
+    ui:
+      mode: auto
+      tui:
+        showReasoning: true
+        maxToolOutputLines: 12
     # Keep the persona to identity and behavior; tool plugins own tool guidance.
     # The loop resolves {{model}} from this agent's configuration.
     persona: |