[audit/high] Add .github/ governance scaffolding

[Displacedtex]

Priority: High

Problem

No issue templates, no PR template, no code of conduct. Newcomers don't know how to report a broken link or propose an entry.

Recommendation

Create the following under .github/:

• CODE_OF_CONDUCT.md — Contributor Covenant v2.1 template.
• ISSUE_TEMPLATE/broken_link.yml — prompts for URL, row number, date.
• ISSUE_TEMPLATE/new_entry.yml — prompts for name, URL, category, why it belongs.
• PULL_REQUEST_TEMPLATE.md — checkbox: link tested, category chosen, format follows CONTRIBUTING.
• FUNDING.yml — surface sponsor options (commit history shows prior sponsorship churn; make policy explicit).

Acceptance criteria

• Opening a new issue surfaces templates.
• Opening a new PR auto-populates the PR body.
• Profile shows the Code of Conduct.

Part of the repo audit backlog. Related: #4 (CONTRIBUTING.md).