feat(cli): add channel-aware update notifier (#265)

* feat(cli): show cached update notices after commands

* docs(cli): describe update notices

* fix(cli): type update check environment

* fix(cli): decouple update notice display from refresh and harden suppression

Display a cached "update available" notice based solely on the lastNoticeAt
24h throttle, independent of checkedAt refresh freshness, matching the design's
independent display/refresh decisions. Suppress the check unconditionally under
--json, CI, and non-TTY before consulting output-mode preferences, so a
KTX_OUTPUT=pretty override can no longer make CI/non-TTY contexts phone npm.

packages/cli/package.json

@@ -73,6 +73,7 @@
     "pg": "^8.21.0",
     "posthog-node": "^5.34.9",
     "react": "^19.2.6",
+    "semver": "^7.8.1",
     "simple-git": "3.36.0",
     "snowflake-sdk": "^2.4.2",
     "yaml": "^2.9.0",
@@ -86,6 +87,7 @@
     "@types/node": "^25.9.1",
     "@types/pg": "^8.20.0",
     "@types/react": "^19.2.15",
+    "@types/semver": "^7.7.1",
     "@vitest/coverage-v8": "^4.1.7",
     "ajv": "8.20.0",
     "ink-testing-library": "^4.0.0",