Add system questions reference to tenant recipes page

[jasnoyaeger]

Summary

• Add a complete System Questions Reference section to the Tenant Recipes page documenting all 23 built-in system questions across 4 sections (Tenant, Nodes, Network)
• Each question includes its variable name, display label, type, default value, and whether it is enabled by default
• Includes a tip noting that custom questions (e.g., expiration dates) can be added beyond the built-in set

Context

• All 23 system questions were validated by creating a test tenant recipe on a live VergeOS 26.1.2 system and capturing the full questions list
• Issue 1 (remove stale POC reference) is addressed separately in PR Remove outdated 30-Day Trial (POC) recipe reference #395
• Notable finding: the "Expiration Date" question mentioned in the issue does not exist as a built-in system question — it would need to be created as a custom question

Test plan

• Verify the tenant recipes page renders correctly at /product-guide/automation/tenant-recipes/
• Confirm all three reference tables (Tenant, Nodes, Network) display properly
• Verify the tip admonition at the end of the section renders correctly

Addresses #392

🤖 Generated with Claude Code

[sethesterline]

tested offline. looks good