F9: smoke checklist + performance budgets in CI

- docs/SMOKE.md: the F9 capability checklist — every carried-over harness
  capability mapped to at least one automated case (test target) or a
  manual probe with its observable, per the PRD acceptance rule.
- scripts/bench.sh: enforces both PRD performance budgets and fails CI on
  a miss — `kigi --version` p95 <= 50ms via hyperfine, and TUI first
  frame <= 300ms measured through the pty harness (real vt100 emulator
  answering terminal queries) via the new scripts/first-frame.scenario.json.
  Local run: p95 10.1ms, first frame 134ms.
- pty harness: StepOutcome gains elapsed_ms (stamped per step by the
  scripted runner) — a leading wait_for_text step's elapsed IS the
  spawn-to-first-paint latency the budget reads.
- CI: new `perf` job (macOS + Linux) building the release binaries and
  running scripts/bench.sh.

.github/workflows/ci.yml

@@ -50,3 +50,30 @@ jobs:
       - uses: Swatinem/rust-cache@v2
       - name: cargo test
         run: cargo test --workspace --locked
+
+  perf:
+    name: performance budgets (${{ matrix.os }})
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [macos-14, ubuntu-24.04]
+    runs-on: ${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install toolchain (rust-toolchain.toml)
+        run: rustup show
+      - name: Install dotslash (protoc launcher)
+        run: cargo install dotslash --locked
+      - uses: Swatinem/rust-cache@v2
+      - name: Install hyperfine (macOS)
+        if: runner.os == 'macOS'
+        run: brew install hyperfine
+      - name: Install hyperfine (Linux)
+        if: runner.os == 'Linux'
+        run: sudo apt-get update && sudo apt-get install -y hyperfine
+      - name: Build release binaries
+        run: |
+          cargo build --release -p kigi-bin --locked
+          cargo build --release -p kigi-pager-pty-harness --bin pty-scenario --locked
+      - name: Enforce performance budgets
+        run: scripts/bench.sh target/release/kigi