docs: remove internal engineering docs; docs must be tool- or story-relevant

Operator policy: docs in the public repo must help (a) a user
deploying certctl or (b) the product story. Internal engineering
process documentation belongs in cowork/ scratchpads or in git
commit history, not docs/.

Removed (docs/contributor/, 8 files, 2,323 lines):
  - release-sign-off.md         — internal release-day checklist
  - ci-pipeline.md              — what runs in CI (internal)
  - ci-guards.md                — what the guards are (internal)
  - testing-strategy.md         — internal testing strategy
  - qa-test-suite.md            — internal QA reference (445 lines)
  - qa-prerequisites.md         — internal QA setup
  - gui-qa-checklist.md         — manual GUI QA checklist
  - test-environment.md         — 1,103-line redundant with
                                  docs/getting-started/quickstart.md +
                                  docs/getting-started/advanced-demo.md

Removed supporting script:
  - scripts/qa-doc-seed-count.sh — CI guard for the deleted
                                   qa-test-suite.md seed-data table

Cross-reference cleanup:
  - README.md: dropped the Contributor audience row + footer
    pointer to docs/contributor/.
  - Makefile: dropped `verify-docs` target + qa-stats comment refs.
  - .github/workflows/ci.yml: dropped the QA-doc seed-count drift
    CI step + dead comment refs.
  - docs/reference/cli.md: repointed qa-prerequisites.md → quickstart.md.
  - docs/operator/performance-baselines.md: dropped ci-pipeline.md
    cross-ref.
  - scripts/ci-guards/README.md: dropped the 'Guards explicitly
    NOT here' section that referenced the deleted QA-doc guards.

G-3 env-docs-drift guard improvements (a real consequence: deleting
the contributor docs surfaced that some env vars only had a home
there). Refit the guard to the new doc topology:
  - Defined-scan widened from `config.go + cmd/*` to all of `cmd/ +
    internal/` (production code), excluding `*_test.go` — catches
    service-layer env vars like CERTCTL_STEPCA_ROOT_CERT and
    CERTCTL_ZEROSSL_EAB_URL that were previously invisible to the
    guard.
  - Docs-scan widened to include deploy/ENVIRONMENTS.md (the
    canonical env-var inventory table — should have been in scope
    from day one). Kept narrow to README + docs/ + deploy/helm/ +
    ENVIRONMENTS.md to avoid pulling in compose/test fixtures.
  - ALLOWED filter now applies to both DOCS_ONLY and CONFIG_ONLY
    directions, so dynamic per-profile dispatch surfaces
    (CERTCTL_SCEP_PROFILE_<NAME>_*, CERTCTL_EST_PROFILE_<NAME>_*,
    CERTCTL_QA_*) don't need static doc entries.
  - Added CERTCTL_SCEP_PROFILE_[A-Z_]+ and CERTCTL_EST_PROFILE_[A-Z_]+
    to ALLOWED for the same reason.

deploy/ENVIRONMENTS.md: added CERTCTL_ZEROSSL_EAB_URL row — real
operator override (overrides the ZeroSSL EAB-credentials endpoint;
read at internal/connector/issuer/acme/acme.go:372) that was
defined in Go source but never documented. G-3 caught it after the
defined-scan widened.

scripts/ci-guards/S-1-hardcoded-source-counts.sh: removed dead
WORKSPACE-CHANGELOG.md allowlist entry (the file was deleted in
the prior workspace cleanup).

Verified:
  All 35 scripts/ci-guards/*.sh green (FAIL=0).
  No remaining references to docs/contributor/ or qa-doc-seed-count
  in tracked files.

Makefile

@@ -1,4 +1,4 @@
-.PHONY: help build run test lint verify verify-docs verify-deploy loadtest acme-cert-manager-test acme-rfc-conformance-test keycloak-integration-test okta-smoke-test benchmark-auth benchmark-auth-coldcache clean docker-up docker-down migrate-up migrate-down generate test-cover frontend-build qa-stats
+.PHONY: help build run test lint verify verify-deploy loadtest acme-cert-manager-test acme-rfc-conformance-test keycloak-integration-test okta-smoke-test benchmark-auth benchmark-auth-coldcache clean docker-up docker-down migrate-up migrate-down generate test-cover frontend-build qa-stats
 
 # Default target - show help
 help:
@@ -16,7 +16,6 @@ help:
 	@echo "  make lint           Run linter (golangci-lint)"
 	@echo "  make fmt            Format code with gofmt"
 	@echo "  make verify         Pre-commit gate: fmt + vet + lint + test (CI-parity)"
-	@echo "  make verify-docs    Pre-tag gate:    QA-doc drift checks (operator-facing docs)"
 	@echo "  make verify-deploy  Pre-push gate:   digest validity + OpenAPI parity + docker build smoke"
 	@echo "  make loadtest       k6 throughput run against postgres + certctl (NOT in verify; manual + cron only)"
 	@echo ""
@@ -119,23 +118,6 @@ verify:
 	@echo ""
 	@echo "verify: PASS — safe to commit"
 
-# verify-docs: pre-tag gate. Runs the QA-doc seed-count drift guard
-# that ci-pipeline-cleanup Phase 11 / frozen decision 0.13 moved out
-# of CI (was per-push blocking; now operator-runs pre-tag). Protects
-# docs/contributor/qa-test-suite.md::Seed Data Reference from
-# drifting vs migrations/seed_demo.sql. Operator-facing docs only —
-# not product-affecting.
-#
-# The QA-doc Part-count drift guard retired in the 2026-05-04 docs
-# overhaul Phase 5 when docs/testing-guide.md was pruned (its content
-# dispersed across the audience-organized doc tree); the Part-count
-# class no longer exists outside the qa_test.go file itself.
-verify-docs:
-	@echo "==> QA-doc seed-count drift"
-	@bash scripts/qa-doc-seed-count.sh
-	@echo ""
-	@echo "verify-docs: PASS — safe to tag"
-
 # verify-deploy: optional pre-push gate. Runs the digest-validity check,
 # the OpenAPI ↔ handler parity check, and a Docker build smoke for the
 # production images (server + agent only — fast subset for local; CI
@@ -313,13 +295,10 @@ frontend-build:
 	cd web && npm ci && npx vite build
 	@echo "Frontend build complete"
 
-# QA Suite Stats — Bundle P / Strengthening #8.
-# Single source-of-truth for every count claim in
-# docs/contributor/qa-test-suite.md. The Strengthening #6 CI drift guards
-# (now scoped to the seed-count class only — the Part-count class retired
-# in the 2026-05-04 docs overhaul Phase 5 when testing-guide.md was
-# pruned) consume the same numbers, eliminating the doc-drift class
-# structurally.
+# qa-stats: snapshot of the test-suite size at the current commit.
+# Backend Go tests + subtests + fuzz targets + skipped sites, plus the
+# seed-data counts in migrations/seed_demo.sql. Useful before a release
+# to spot-check that no whole layer dropped off.
 qa-stats:
 	@echo "=== certctl QA Suite Stats ==="
 	@echo "Date: $$(date +%Y-%m-%d)"