chore: add raios-policy.toml, SIGMAP.md, keyboard module refactor

- raios-policy.toml: example Security Kernel config (sandbox paths,
  tool allow/deny/confirm rules, egress domain allow/blocklist)
- SIGMAP.md: Antigravity-generated codebase signature map
- keyboard.rs (1032 lines) → keyboard/ module (6 sub-files: dashboard,
  editor, health, mod, project, setup) — Antigravity refactor
- .gitignore: add *.bak and *_bak/ patterns

Author: alazndy

.gitignore

@@ -3,3 +3,5 @@
 .DS_Store
 *.pdb
 *.exe
+*.bak
+*_bak/