Establish repository-specific contribution governance

[srpatcha]

Problem

eBrowser combines a C11 HTML/CSS/DOM/rendering engine with network, privacy, TLS, sandbox, UI, embedded, SDL2, WebAssembly, mobile, extension, and web-app surfaces. Its current agent guidance is generic, and its pull request template only offers an optional related-issues section instead of requiring a GitHub-recognized same-repository closing issue. The published Wiki also lacks a source-controlled snapshot.

This leaves security-sensitive browser changes without repository-specific operating guidance and weakens traceability between implementation and reviewed intent.

Proposed governance baseline

• Replace the generic root AGENTS.md with eBrowser-specific architecture, C11 portability, security boundaries, and test guidance.
• Add .github/workflows/linked-issue.yml from the organization canonical template, pinning both references to 92cb596c773496ec4df76717e8acf0e6b7700f73.
• Reconcile the existing pull request template to require a recognized same-repository closing issue while preserving change type, native testing, screenshots/logs, and additional-notes sections.
• Mirror the six published Wiki pages into docs/wiki/.

Acceptance criteria

• The workflow uses only read permissions and an immutable full policy SHA.
• AGENTS.md distinguishes core, public headers, ports, security/network modules, and companion surfaces and names the correct CMake/CTest/Python checks.
• The PR template starts with a concrete Fixes #123 same-repository requirement and contains no control-character-corrupted labels.
• The six Wiki Markdown files match the published Wiki revision byte-for-byte and their relative links resolve.
• YAML, authored Markdown, whitespace, and the repository Python suites validate.