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.

skills/github/github-issues/SKILL.md

@@ -28,8 +28,8 @@ if command -v gh &>/dev/null && gh auth status &>/dev/null; then
 else
   AUTH="git"
   if [ -z "$GITHUB_TOKEN" ]; then
-    if _hermes_env="${HERMES_HOME:-$HOME/.hermes}/.env"; [ -f "$_hermes_env" ] && grep -q "^GITHUB_TOKEN=" "$_hermes_env"; then
-      GITHUB_TOKEN=$(grep "^GITHUB_TOKEN=" "$_hermes_env" | head -1 | cut -d= -f2 | tr -d '\n\r')
+    if [ -f ~/.hermes/.env ] && grep -q "^GITHUB_TOKEN=" ~/.hermes/.env; then
+      GITHUB_TOKEN=$(grep "^GITHUB_TOKEN=" ~/.hermes/.env | head -1 | cut -d= -f2 | tr -d '\n\r')
     elif grep -q "github.com" ~/.git-credentials 2>/dev/null; then
       GITHUB_TOKEN=$(grep "github.com" ~/.git-credentials 2>/dev/null | head -1 | sed 's|https://[^:]*:\([^@]*\)@.*|\1|')
     fi