docs: add a public-safe ontology workflow tutorial

[kms970]

Goal

Add a short public-safe tutorial that walks a new user through the conversation-to-ontology workflow from synthetic input to compiled Mindpack output.

Suggested scope

• Use only synthetic example text.
• Show these commands:
  • init-ontology
  • ingest-conversation
  • inspect review/pending.jsonl
  • approve-candidates
  • compile-ontology
  • validate
  • run
• Add the tutorial under docs/ and link it from README.md.

Acceptance criteria

• The tutorial can be copy-pasted on macOS/Linux with python3.
• It does not commit generated dist/ output.
• It does not include real conversations, names, private paths, credentials, or customer data.
• python3 -m pytest -q still passes.

Why this is a good first issue

It is documentation-first, has clear commands to verify, and helps contributors understand Mindpack's privacy-first ontology workflow.