feat: restore CI/release, prompt contracts, faster install (0.9.33)

Bring back Gitea CI + auto-publish; share release helpers; strengthen multi-turn
tool/job prompts with a unit contract; ccache/make help and --release bootstrap.

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

scripts/package_linux.sh

@@ -3,9 +3,12 @@
 # dist/cst-agent-VERSION-linux-ARCH.tar.gz (+ .sha256).
 #   scripts/package_linux.sh x86_64|x86|aarch64
 # CST_LINUX_CHECK=1 also runs `make check` (only where the binaries can run).
-# Builds in the source tree, so the tree is cleaned first.
+# CST_FORCE_REBUILD=1 forces a clean tree; otherwise same compiler+version
+# reuses object files (much faster CI/local repacks).
 set -euo pipefail
 ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+# shellcheck source=lib_release.sh
+. "$ROOT/scripts/lib_release.sh"
 ARCH="${1:?usage: $0 x86_64|x86|aarch64}"
 PREFIX="$ROOT/third_party/prefix-linux-$ARCH"
 cd "$ROOT"
@@ -24,9 +27,20 @@ unset PKG_CONFIG_PATH CC CFLAGS LDFLAGS
 mk=(make CC="${T}gcc" AR="${T}ar" STATIC=1
   CFLAGS="-std=c11 -Wall -Wextra -O2 -g -Werror")
 
-make clean >/dev/null
-make -C vendor/sashidown clean >/dev/null 2>&1 || true
+stamp=".gen/release-linux-$ARCH.stamp"
+want="$(cst_build_stamp "${T}gcc")"
+if [[ "${CST_FORCE_REBUILD:-0}" == 1 || ! -f cst-agent || ! -f "$stamp" ||
+  "$(cat "$stamp" 2>/dev/null || true)" != "$want" ]]; then
+  echo "==> clean rebuild ($ARCH)"
+  make clean >/dev/null
+  make -C vendor/sashidown clean >/dev/null 2>&1 || true
+else
+  echo "==> incremental rebuild ($ARCH, stamp match)"
+fi
 "${mk[@]}" -j"$(nproc)" cst-agent
+mkdir -p .gen
+printf '%s\n' "$want" >"$stamp"
+
 if "${T}readelf" -l cst-agent | grep -q 'Requesting program interpreter'; then
   echo "cst-agent is dynamically linked" >&2
   exit 1
@@ -35,7 +49,7 @@ if [[ "${CST_LINUX_CHECK:-0}" == 1 ]]; then
   "${mk[@]}" check
 fi
 
-ver="$(sed -n 's/^#define CST_VERSION_\(MAJOR\|MINOR\|PATCH\) \([0-9]*\)$/\2/p' include/cst_version.h | paste -sd.)"
+ver="$(cst_version)"
 name="cst-agent-$ver-linux-$ARCH"
 rel="dist/$name"
 rm -rf "$rel"
@@ -44,8 +58,6 @@ cp -f cst-agent "$rel/cst-agent"
 "${T}strip" "$rel/cst-agent"
 cp -f README.md "$rel/README.md"
 echo "$ver" >"$rel/VERSION"
-tgz="dist/$name.tar.gz"
-tar -C dist -czf "$tgz" "$name"
-(cd dist && sha256sum "$name.tar.gz" >"$name.tar.gz.sha256")
+tgz="$(cst_pack_tgz dist "$name")"
 ls -la "$rel"
 echo "$ROOT/$tgz"