KanataDefcfg uses only standard-library types; Foundation is not needed.
Addresses automated review feedback on #859.

Address non-blocking review feedback on #859 (output-neutral):
- render(): assert trailer begins with a newline when non-empty, and that
  managed-repeat delay/interval are both set or both nil — both are currently
  unreachable footguns, now guarded.
- standard(): requirePriorIdleMs is now Int? (nil = omit) instead of using a
  magic 0 sentinel at the factory boundary; the caller maps its 0 sentinel.
- Document that minimalSafe/validationWrapper render identically by design and
  that allowCommandActions:false omits danger-enable-cmd (kanata defaults off).
- Trim the redundant generator comment to keep only the non-obvious rationale.
- Add testMinimalSafeAndValidationWrapperShareOutputByDesign.

Rendered output is unchanged for every emitter (asserts hold for all inputs;
0->nil mapping preserves prior behavior). Golden/unit pins still apply.

Review noted the render() assert is debug-only, so it can't protect a release
daemon if a caller half-pairs managed-repeat delay/interval. Take them as a
single (delayMs, intervalMs)? tuple in KanataDefcfg.standard() so the only real
construction path cannot half-set them. Stored properties stay Int? to preserve
Equatable synthesis; the assert remains as a debug backstop for the internal
init. Output is unchanged (tuple maps to the same two optionals).

Audit quick wins (no code changes):

- Untrack 24 MB of committed build artifacts (coverage/, coverage-full/,
  search-index.json) and add .gitignore guards. These regenerate in CI and
  nothing references them.
- Remove the accidental literal '~/Library/Application Support/KeyPath/keypath.kbd'
  directory committed at the repo root (a script/test that didn't expand $HOME),
  and add a /~/  .gitignore guard so it can't recur.
- CONTRIBUTING.md: replace the absolute /Users/malpern/... SECURITY.md link with a
  repo-relative one, and correct the stale 'I Want To...' file pointers to the
  current module layout (Sources/KeyPath/* -> Sources/KeyPathAppKit/*, KeyPathCore,
  KeyPathInstallationWizard). ContentView/SystemStatusChecker no longer exist;
  point at their successors.
- CLAUDE.md: fix the stale note about a non-existent Tests/KeyPathAppKitTests/
  directory; list the four real, compiled test targets.

Remaining CONTRIBUTING staleness (architecture prose mentioning ContentView/
KanataManager, and the Sources/KeyPath/ directory tree) is left for a focused
docs refresh.