perf: add pnpm --prefer-offline and smart Rust checking

- Add --prefer-offline to pnpm install to avoid network calls
- Skip cargo check when no Rust files (.rs, .toml, Cargo.lock) changed
- Should provide modest speedup for commits without Rust changes

check-history.sh

@@ -115,9 +115,9 @@ build_frontend() {
 
         [ "$VERBOSE" -eq 1 ] && echo "[BUILD_DEBUG] Running pnpm install..." || true
         if [ "$VERBOSE" -eq 1 ]; then
-            pnpm install --frozen-lockfile </dev/null
+            pnpm install --frozen-lockfile --prefer-offline </dev/null
         else
-            pnpm install --frozen-lockfile </dev/null >/dev/null 2>&1
+            pnpm install --frozen-lockfile --prefer-offline </dev/null >/dev/null 2>&1
         fi || {
             echo "❌ pnpm install failed"
             return 1
@@ -194,13 +194,19 @@ check_commit() {
             [ "$VERBOSE" -eq 1 ] && echo "[CHECK_DEBUG] No rfc-edge-frontend directory found, skipping frontend build" || true
         fi
 
+        # Check if Rust files changed in this commit
+        if git diff --name-only "${commit}^..${commit}" 2>/dev/null | grep -qE '\.(rs|toml)$|Cargo\.lock'; then
+            [ "$VERBOSE" -eq 1 ] && echo "[CHECK_DEBUG] Rust files changed, running cargo check" || true
             echo "→ Running cargo check…"
-        [ "$VERBOSE" -eq 1 ] && echo "[CHECK_DEBUG] Starting cargo check" || true
             if ! cargo check --quiet; then
                 echo "❌ Cargo check failed"
                 exit 1
             fi
             [ "$VERBOSE" -eq 1 ] && echo "[CHECK_DEBUG] Cargo check completed successfully" || true
+        else
+            [ "$VERBOSE" -eq 1 ] && echo "[CHECK_DEBUG] No Rust files changed, skipping cargo check" || true
+            echo "→ Skipping cargo check (no Rust changes)"
+        fi
 
         echo "✓ OK"
     ) >"$log" 2>&1