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.

.github/workflows/tests.yml

@@ -55,31 +55,15 @@ jobs:
 
       - name: Install uv
         uses: astral-sh/setup-uv@d4b2f3b6ecc6e67c4457f6d3e41ec42d3d0fcb86  # v5
-        with:
-          # Persist uv's download/wheel cache (~/.cache/uv) across runs.
-          # Keyed on the dependency manifests, so the cache is reused until
-          # pyproject.toml or uv.lock changes. `uv sync` still runs every
-          # time, but resolves from the warm cache instead of re-downloading
-          # and re-building wheels.
-          enable-cache: true
-          cache-dependency-glob: |
-            pyproject.toml
-            uv.lock
 
       - name: Set up Python 3.11
         run: uv python install 3.11
 
       - name: Install dependencies
-        # `uv sync --locked` installs the exact pinned set from uv.lock (and
-        # fails if the lock is out of sync with pyproject.toml), giving a
-        # reproducible env. It also creates .venv itself, so no separate
-        # `uv venv` step is needed.
-        run: uv sync --locked --python 3.11 --extra all --extra dev
-
-      - name: Minimize uv cache
-        # Optimized for CI: prunes pre-built wheels that are cheap to
-        # re-download, keeping the persisted cache small and fast to restore.
-        run: uv cache prune --ci
+        run: |
+          uv venv .venv --python 3.11
+          source .venv/bin/activate
+          uv pip install -e ".[all,dev]"
 
       - name: Run tests (slice ${{ matrix.slice }}/6)
         # Per-file isolation via scripts/run_tests_parallel.py: discovers
@@ -177,31 +161,15 @@ jobs:
 
       - name: Install uv
         uses: astral-sh/setup-uv@d4b2f3b6ecc6e67c4457f6d3e41ec42d3d0fcb86  # v5
-        with:
-          # Persist uv's download/wheel cache (~/.cache/uv) across runs.
-          # Keyed on the dependency manifests, so the cache is reused until
-          # pyproject.toml or uv.lock changes. `uv sync` still runs every
-          # time, but resolves from the warm cache instead of re-downloading
-          # and re-building wheels.
-          enable-cache: true
-          cache-dependency-glob: |
-            pyproject.toml
-            uv.lock
 
       - name: Set up Python 3.11
         run: uv python install 3.11
 
       - name: Install dependencies
-        # `uv sync --locked` installs the exact pinned set from uv.lock (and
-        # fails if the lock is out of sync with pyproject.toml), giving a
-        # reproducible env. It also creates .venv itself, so no separate
-        # `uv venv` step is needed.
-        run: uv sync --locked --python 3.11 --extra all --extra dev
-
-      - name: Minimize uv cache
-        # Optimized for CI: prunes pre-built wheels that are cheap to
-        # re-download, keeping the persisted cache small and fast to restore.
-        run: uv cache prune --ci
+        run: |
+          uv venv .venv --python 3.11
+          source .venv/bin/activate
+          uv pip install -e ".[all,dev]"
 
       - name: Packaged-wheel i18n smoke test
         run: |