Extract consultation/visit records from this medical document. Return a JSON array or null.

Each entry:
- type: visit subtype ("visit", "referral", "follow_up", "letter")
- value: (empty)
- summary: provider + date, e.g. "provider_name, Nov 2025"
- timestamp: "YYYY-MM-DD" if date mentioned
- data: {"provider": "...", "specialty": "...", "location": "...", "reason": "..."}

Every entry MUST come from text explicitly present in the document. Do NOT infer or assume.
Return null if nothing relevant is explicitly described.

Document:
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