OpenTerminal v0.2.1: terminal suite with SSH, split panes, themes and keyword highlighting

- Local terminal (node-pty) + SSH sessions (ssh2) with unified data plane
- dockview split panes, per-group '+' tab bar button, layout templates
- Session replay buffer (late-subscriber catch-up), host key pinning,
  credential encryption via safeStorage
- 12 builtin themes + custom theme editor, system font enumeration
- Keyword highlighting: regex rules with priority, ANSI truecolor injection,
  chunk-boundary-safe stream (carry-over of partial escape sequences)
- Dark antd theme app-wide, settings dialog redesign, error boundary
- Tests: ssh loopback, session e2e, highlight split-chunk regression

.gitignore

@@ -0,0 +1,17 @@
+# dependencies
+node_modules/
+
+# build output
+out/
+dist/
+tests/.session-e2e.cjs
+
+# research artifacts (XTerminal reverse-engineering notes, not part of the app)
+research/
+
+# logs / misc
+*.log
+.DS_Store
+
+# ts build info
+*.tsbuildinfo