docs: publish CoreLink v1 30-minute quickstart

[jaavid]

Related: #3

Replaces draft PR #8 using the same validated branch because the connected GitHub integration could not execute the Ready-for-review mutation.

What changed

• publishes a contract-backed 30-minute v1 quickstart for bearer auth, tenant scoping, Device and Command calls
• documents the current credential boundary without inventing a token-issuance endpoint
• covers idempotent command submission, standard problem responses, safe retries and tenant-isolation verification
• links the quickstart from versioned docs indexes
• extends Documentation CI with contract markers

Contract boundary

Targets current 1.0.0-draft Device + Command public contract. TypeScript/Python remain prerelease Alpha; no Stable SDK or public-production endpoint claim is introduced.

Validation

Documentation CI on the unchanged head 88ae7da456d8c8abdf2c0d2a1e84aa5e467c5e3a previously completed successfully (run 31123081823).