chore(docs): remove 20 version-archaeology docs pinned to v1.0/v1.2/v1.3

Each file pins to a long-shipped milestone or contains numbers and
prerequisites (Python 3.8+, Docker, 12/30/48 prover counts) that
contradict current reality (v2.3.0, 105 backends, Podman/Guix only).
docs/ROADMAP.md, .machine_readable/6a2/STATE.a2ml, CHANGELOG.md, and
the kept release_notes_v{1.2,1.3}.md are the durable historical
sources. All 20 are recoverable via git history.

Removed:
  - docs/QUICKSTART.md                       v1.3, Python 3.8+
  - docs/FUTURE_DEVELOPMENT_ROADMAP.md       explicitly superseded by
                                             docs/ROADMAP.md
  - ROADMAP.adoc (root)                      v2.0 era, "48 backends"
  - docs/MVP-1.0{,-MISSING,-DEPS}.adoc       v1.0 MVP checklists
  - docs/TRAINING_DATA_EXPANSION.md          targets 1k; have 66 674
  - docs/deployment/DEPLOYMENT.md            references Docker
  - docs/deployment/V1.2_DEPLOYMENT_GUIDE.md v1.2.0-specific
  - docs/DELIVERABLES.md                     mislabelled CVC5 work-order
  - docs/implementation/PROVER_IMPLEMENTATION_STATUS.md  "12/12 v1.2"
  - 6 × docs/reports/* frozen v1.3-era reports
  - docs/releases/RELEASE_NOTES.md           duplicate of v1.3 notes;
                                             v1.2 and v1.3 release
                                             notes retained
  - TOPOLOGY.md + docs/STATE-VISUALIZER.adoc superseded by STATE.a2ml

https://claude.ai/code/session_01YPqu7gti4azBach6ZvpRFJ

Author: claude