feat(knowledge): add sourced dermatology resources

[Davidson3556]

What does this change?

Adds four educational dermatology resources that MCP clients can read without credentials or network access:

• molecare://knowledge/sun-protection explains SPF, UVA labelling, sunscreen use, shade and clothing
• molecare://knowledge/common-benign-lesions describes several common non-cancerous growths while making clear that appearance alone cannot identify a lesion
• molecare://knowledge/skin-self-examination provides a head-to-toe observation and recording routine
• molecare://knowledge/dermatology-appointment explains how someone can prepare and what may happen during a routine skin appointment

Each resource includes a non-diagnostic scope boundary, the standard medical disclaimer, and dated source links from the NHS, American Academy of Dermatology, DermNet, American Family Physician, or an NHS hospital trust. The wording is paraphrased and stays educational: it does not classify a lesion, assign a risk level, or recommend an urgency.

The README and resource-list smoke tests now cover the expanded surface. A focused test also checks that every new resource is readable, names HTTPS sources, carries its disclaimer and boundary, and avoids diagnostic or triage language.

Related issue

Fixes #5

Checklist

• npm run build passes
• Server starts and all four resources can be listed and read in the mock-mode integration test
• No new tools; tool schemas are unchanged
• Works in mock mode (no credentials configured)
• No secrets, real hostnames, account IDs, or personal data added
• No patient images added, including in tests
• Every new medical resource carries a non-diagnostic disclaimer

npm test: 82/82 passing.

Does this change a tool's response shape?

No tool response changes.

The resource surface changes additively: four new resource URIs are listed. Those new resources include a top-level sources array containing title, publisher, url, and accessed. Existing resource URIs and payloads are unchanged.

[YauhenBichel]

Thank you for adding sources, this makes the content much easier to trust! One fix please: the UCLH "Skin biopsy" link is a neurology page (a skin biopsy for nerve tests), not about moles. Could you use the NHS page instead? https://www.nhs.uk/conditions/melanoma-skin-cancer/tests-and-next-steps-for-melanoma-skin-cancer/
Because this is health text, a clinician will also read it before we merge.