feat: add instruct command with platform reference for humans and agents

Adds `shsf instruct` as a first-stop command covering what SHSF is,
a CLI command group overview, quick-start steps for humans, and the full
AIDOC function authoring reference for AI agents. The program description
and help footer now prompt users to run `shsf instruct` before anything else.

Bumps version to 2.3.3.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "shsf-cli",
-  "version": "2.3.2",
+  "version": "2.3.3",
   "description": "Production-ready command-line interface and agent bridge for SHSF.",
   "type": "module",
   "files": [