docs: wipe all documentation for clean reference-docs rewrite

User-requested full doc nuke. The existing docs were a mix of
Java-era specs (now obsolete after Phase 6 cutover), point-in-time
plans (Go-port phases 1-6, OOM-fix), and partial v0.4.0-state
references that didn't form a coherent reference. Wiping them for
a single clean rewrite is faster than re-anchoring each file.

Deleted (24 files / ~5.9k lines):

  AGENTS.md, CHANGELOG.md, CLAUDE.md, PROJECT_SUMMARY.md,
  README.md, SECURITY.md

  docs/audits/2026-04-28-serve-path-prod-readiness*.md (2)
  docs/codeiq.yml.example
  docs/plans/2026-04-2[78]-sub-project-*.md (2)
  docs/specs/2026-04-2[78]-*-design.md (2)
  docs/superpowers/baselines/2026-04-17/{BASELINE,PHASE-B-EXIT-GATE}.md
  docs/superpowers/plans/2026-05-13-enrich-oom-fix.md

  shared/runbooks/{aks-oom-quick-fix,aks-read-only-deploy,
    engineering-standards,first-time-setup,release-go,release,
    rollback,test-strategy}.md

Preserved:

  LICENSE                                  — legal artifact
  testdata/fixture-minimal/README.md       — test fixture content
                                              (exercises detectors)
  .github/workflows/*                      — CI configs, not docs
  source code                              — comments stay with code
  .goreleaser.yml                          — references README.md
                                              via `files:` pattern;
                                              will silent-skip until
                                              README returns
  .github/workflows/release-darwin.yml     — copies LICENSE/README/
                                              CHANGELOG with
                                              `|| true`; degrades
                                              gracefully

The release pipeline keeps working; release archives just won't
include README/CHANGELOG until the new docs land.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: aksOps