fix: scope facility doctor agent checks to YAML frontmatter

[o-mid]

Addresses doctor false pass and false fail against the 0.12 agent contract.

facility doctor applied name, model, trigger, and forbidden-key regexes to the whole agent file. Prompt text such as a GitHub permissions: example failed the check, and a wrong frontmatter name: could be hidden by repeating the expected name in the prompt. Quoted model ids with spaces also failed.

Doctor now splits YAML frontmatter from the prompt, accepts mcp and ui triggers (already valid at runtime), and reads the model as a YAML string scalar. Comment-only values (model: # choose a model) and unclosed quotes are rejected, matching the server.

Test plan

• pnpm --filter @theagilemonkeys/facility test
• CLI suite 10 consecutive passes
• Confirm a prompt that contains permissions: still passes
• Confirm frontmatter permissions: still fails
• Confirm name: builder only in the prompt does not satisfy builder.md
• Confirm model: "gpt-5.6-sol with spaces" passes
• Confirm model: # choose a model fails
• Confirm model: "unclosed fails
• Confirm an agent with only mcp and ui triggers passes

[adrian-lorenzo]

Thanks for fixing the frontmatter scoping.

The relaxed model check now accepts model: # choose a model and unclosed quoted values, although the server rejects both. Please validate the model value while preserving quoted names with spaces, and add regression tests for these cases.

[o-mid]

@adrian-lorenzo Thanks, that was a real hole.
\S treated # and an opening quote as a model ID.
Follow-up parses the model as a YAML string scalar, so quoted names with spaces still pass. model: # choose a model and unclosed quotes fail, same as the server. Tests cover both.