ISSUE-022 — ADR-025 pragmatic SOLID refactor

[shivaram19]

• Functional surgeon view: Volatile boundaries (LLM, scraper, DB) are behind ports; legacy src/ is removed via Strangler Fig.
• Acceptance criteria:
  1. ADR-025 accepted.
  2. pipeline/interfaces.py ports cover scraper and LLM.
  3. Empty src/ tree deleted.
  4. All tests pass.
• Dependencies: status:blocked until ADR-025 accepted.