chore: remove stray root artifacts

[vku2018]

Summary

• remove tracked root artefact files listed in (chore) Remove AI-generated artefact files and stray files from repository root #227 that are still present
• replace the root PULL_REQUEST_TEMPLATE.md artefact with a usable .github/PULL_REQUEST_TEMPLATE.md
• update the docs hub so it no longer links to deleted root artefact docs

Closes #227

Validation

• PASS git diff --cached --check before commit
• PASS git ls-files | Select-Object -First 60 after staging: deleted root artefacts no longer appear in the first tracked paths; .github/PULL_REQUEST_TEMPLATE.md does
• PASS explicit path check: 0, GABC...WXYZ, MICROSERVICES_VISUAL_GUIDE.md, PULL_REQUEST_TEMPLATE.md, RECONCILIATION_QUICKSTART.md, RESILIENCE_IMPLEMENTATION_GUIDE.md, RESILIENCE_QUICK_REFERENCE.md, and TEST_LINTER.md are absent; .github/PULL_REQUEST_TEMPLATE.md exists
• PASS docs-link scan for deleted root artefact links in docs/README.md, README.md, ARCHITECTURE.md, SECURITY_HARDENING_GUIDE.md, and .github
• NOT RUN npm tests/build: cleanup only deletes root artefacts and adjusts docs/template metadata; no source/runtime files changed