opentui(phase3): launcher integration — HERMES_TUI_ENGINE dual-engine

hermes --tui launches the native OpenTUI engine (Bun) when
HERMES_TUI_ENGINE=opentui (env) or display.tui_engine=opentui (config);
Ink stays the default and the shipping path is untouched.

- _resolve_tui_engine() (env > config > ink); refuses opentui on
  Windows/Termux (no Bun) -> falls back to ink with a notice.
- _make_opentui_argv() -> [bun, src/entry.real.tsx] (no build step).
- _bun_bin() with HERMES_BUN override.
- Branch at top of _make_tui_argv BEFORE _ensure_tui_node (Bun-only host
  must not bootstrap Node).
- Gate _launch_tui NODE_OPTIONS/--max-old-space-size on engine==ink (Bun
  is JSC; the V8 flag errors/ignores).

Verified end-to-end via tmux: real hermes --tui -> Bun -> OpenTUI ->
real Python gateway streamed a real reply. No-flag default still ink.

.dockerignore

@@ -63,45 +63,3 @@ data/
 # Compose/profile runtime state (bind-mounted; avoid ownership/secret issues)
 hermes-config/
 runtime/
-
-# ---------- Not needed inside the Docker image ----------
-
-# Desktop app source (Tauri/Electron); never installed in the container
-apps/
-
-# Test suite — not shipped in production images
-tests/
-
-# Documentation site (Docusaurus) and supplementary docs
-website/
-docs/
-
-# Assets only used by the GitHub README
-assets/
-infographic/
-
-# Plugin-level docs (hermes-achievements ships docs/ but the runtime doesn't read them)
-plugins/hermes-achievements/docs/
-
-# Nix / Homebrew / AUR packaging metadata — irrelevant to Docker
-nix/
-flake.nix
-flake.lock
-packaging/
-
-# Design and planning documents
-plans/
-.plans/
-
-# ACP registry manifest (icon + agent.json) — not consumed at runtime
-acp_registry/
-
-# Repo-level dotfiles that are git-only or dev-tooling config
-.env.example
-.envrc
-.gitattributes
-.hadolint.yaml
-.mailmap
-
-# Top-level LICENSE (not matched by *.md); not needed inside the container
-LICENSE