perf(validation): skip warm native rebuilds

[JustYannicc]

What changed

• Added stamp-based up-to-date checks for top-level Swift helpers in scripts/build-native.mjs.
• Added native_helpers.node invalidation keyed by addon sources, binding.gyp, package manifests/lockfile, Electron package, target arch, and build command.
• Added Whisper transcriber invalidation keyed by source, build script/command, framework version/hash/url, and framework bundle mtimes.
• Included Package.resolved and helper build scripts in Parakeet/Soulver rebuild checks.

Why

• Warm native validation was still rebuilding the native addon and Whisper transcriber even when all inputs were unchanged.
• The new checks keep changed sources, package manifests, lock/resolved files, framework inputs, Electron target, arch, and build script changes from being skipped.

Compatibility impact

• No runtime behavior changes intended.
• First run after this patch rebuilds and writes local dist/native stamp files; subsequent unchanged warm runs skip.
• Missing outputs, missing inputs, changed mtimes/sizes, changed commands, changed Electron package/arch, or changed framework metadata force rebuilds.

How tested

• node /opt/homebrew/lib/node_modules/npm/bin/npm-cli.js ci --ignore-scripts
• env PATH=/tmp/supercmd-real-npm-bin:... /usr/bin/time -p node scripts/build-native.mjs
• Stale Swift source regression from the original validation: touch src/native/color-picker.swift, rerun build-native; color-picker rebuilt while other helpers skipped.
• Stale addon regression from the original validation: touch src/native/native-helpers-addon/native_helpers.mm, rerun build-native; node-gyp rebuilt native_helpers.node.
• node --check scripts/build-native.mjs
• node --check scripts/build-whispercpp.mjs
• node --check scripts/build-parakeet.mjs
• node --check scripts/build-soulver-calculator.mjs
• ./node_modules/.bin/tsc -p tsconfig.main.json
• git diff --check 15ee435...HEAD
• Codex LSP diagnostics on scripts/ with severity error

Performance evidence

• Original baseline immediate warm run before patch: real 13.83s, user 13.08s, sys 2.45s; native addon and Whisper transcriber rebuilt, Parakeet/Soulver skipped.
• Original final after warm run: real 0.29s, user 0.23s, sys 0.04s; all targets reported up to date.
• Original addon stale-input rebuild check: real 1.70s and node-gyp rebuilt native_helpers.node.
• Repaired-branch population run: real 64.93s in a fresh worktree with missing native outputs/framework/package builds.
• Repaired-branch immediate warm run: real 0.25s, user 0.21s, sys 0.03s; all targets reported up to date.

Stack validation

• Built on repaired validation base 15ee435 fix(validation): make macos liquid glass dependency optional.
• Branch: codex/perf-native-build-incremental.
• Commit: 9c751bb perf(validation): skip warm native rebuilds.
• PR perf(validation): skip warm native rebuilds #577 repaired in place; no duplicate PR opened.
• Branch diff against 15ee435 contains only scripts/build-native.mjs, scripts/build-whispercpp.mjs, scripts/build-parakeet.mjs, and scripts/build-soulver-calculator.mjs.
• Codex LSP diagnostics: scripts directory scanned for .mjs errors, 50 files capped, 0 files with errors, 0 diagnostics.
• No pnpm-lock.yaml created and generated src/native/soulver-calculator/Package.resolved churn was restored before push.

Replaces

• Native-build warm-overhead candidate from the delegated validation audit.

[JustYannicc]

Superseded by the consolidated validation PR: #578