Harden organization repository surface

[jay-oraclizer]

Summary

• turn the public .github repository into Oraclizer's organization-wide community-health fallback
• add a repository README, BSD-3-Clause license, security, support, contribution, conduct, and governance policies
• add CODEOWNERS, structured issue forms, a Pull Request template, and GitHub Actions Dependabot configuration
• add a dependency-free repository-health workflow pinned to actions/checkout v7.0.1 by full commit SHA
• add a version-controlled 1280x640 social-preview source and PNG

Why

The organization profile README was production-grade, but the repository surface was not. GitHub reported a 25% Community Profile, the default branch had no protection, only two Topics were present, and the repository lacked root guidance and organization-wide fallback policies.

This repository is an organization profile and policy surface, not packaged software. The governance policy therefore records that routine documentation changes do not receive artificial Git tags or Releases. GitHub Topics and the social preview are the correct discovery metadata for this repository type.

Public impact

• repository-specific policies continue to override these defaults
• no private repository URL or visibility is changed
• no release date, audit, deployment, legal-compliance, or production-readiness claim is added
• the existing organization profile content is unchanged

Verification

• node scripts/verify-profile.mjs
• node --check scripts/verify-profile.mjs
• git diff --check
• XML parsing for all three SVG assets
• 1280x640 PNG inspection; 83,546 bytes
• GitHub workflow and issue-form parsing to be confirmed on this PR

Post-merge settings

After the workflow succeeds on main:

• expand Topics to accurate organization technologies and standards
• upload the social preview
• enable squash-only merges, automatic branch deletion, Private Vulnerability Reporting, and secret scanning
• disable unused Issues, Projects, and Wiki on this repository
• activate a default-branch ruleset requiring linear history, Pull Requests, resolved conversations, and the Profile health status check