Initial CST-Agent: portable Linux/Termux/Windows coding agent.

Vendored sashidown, OpenAI-compatible env (OPENAI_*), and bootstrap scripts.

Co-authored-by: Cursor <cursoragent@cursor.com>

scripts/bootstrap_termux.sh

@@ -0,0 +1,31 @@
+#!/data/data/com.termux/files/usr/bin/bash
+# One-shot: clone + build CST-Agent on Android Termux.
+set -euo pipefail
+
+REPO_URL="${CST_AGENT_REPO:-https://git.whcself.xyz/WHC/CST-agent.git}"
+DIR="${1:-CST-agent}"
+
+echo "==> Termux packages"
+pkg install -y git clang make cmake libcurl ncurses-ui-libs 2>/dev/null \
+  || pkg install -y git clang make cmake curl ncurses
+
+if [[ ! -f "$DIR/Makefile" ]]; then
+  echo "==> git clone $REPO_URL -> $DIR"
+  git clone "$REPO_URL" "$DIR"
+fi
+cd "$DIR"
+
+echo "==> cmake build (TUI)"
+cmake -B build -DCMAKE_C_COMPILER=clang -DCST_BUILD_TUI=ON
+cmake --build build -j"$(nproc 2>/dev/null || echo 4)"
+# Also keep Makefile binary path convenience
+cp -f build/cst-agent ./cst-agent 2>/dev/null || true
+
+echo
+echo "OK: ./cst-agent  (or ./build/cst-agent)"
+echo "OpenAI-compatible:"
+echo "  export OPENAI_API_KEY=sk-..."
+echo "  export OPENAI_BASE_URL=https://api.openai.com/v1"
+echo "  export OPENAI_MODEL=gpt-4.1-mini"
+echo "  ./cst-agent --workspace \$HOME"
+echo "Docs: docs/env_openai.md"