docs(v0.3): add #22 Windows support candidate (WSL2 callout + demand-…

[machbuilds]

…gated port)

Consolidates the 2026-05-18 Windows port evaluation (nucleus session windows-port-eval-1779112103) into the v0.3 candidate list so the decision lives with the roadmap, not just the nucleus log.

Two-phase: Phase A WSL2 callout (v0.2.x stopgap), Phase B native port demand-gated. Captures bootstrap-vs-runtime split and half-port pitfall.

Summary

Type of change

• New feature (atom CLI, scaffold content, extras preset)
• Bug fix
• Documentation
• New learning (learnings/<type>/<slug>.md)
• New stack preset (extras/<category>/<preset>/)
• Refactor / hygiene

Generalisation test (if adding to learnings/ or docs/)

Would this help a project unrelated to where it came from?

• Yes — it teaches a pattern, pitfall, or lesson that applies broadly
• Project-specific — moving to my source project's docs instead

If you ticked the first box, also confirm:

• No project-specific names, IDs, or vendor quirks remain
• applies_to: field is set correctly (see docs/LEARNINGS_TAXONOMY.md)

Verification

• Ran atom-setup --bare against a clone copy and the result is correct
• Ran the relevant CLI's smoke test (nucleus add + nucleus search, etc.)
• CI passes locally (npm install && node --check bin/<cli>/bin/<cli>.js)
• No stale references to deprecated names (GBrain, Dockerfile.example, etc.)

Voice check

• Builder-to-builder voice (no AI vocabulary, no em-dashes-as-commas)
• Concrete (file paths, command examples, real numbers — not vague references)
• No corporate hedging