docs(e6): add wiki pages — Sidebar, Footer, Contributing, SECURITY, CODE_OF_CONDUCT

.github/wiki/CODE_OF_CONDUCT.md

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+# Code of Conduct
+
+## Summary
+
+Be direct, be respectful, and focus on the work.
+
+## Standards
+
+Constructive behavior:
+
+- Technical criticism aimed at code and ideas, not people
+- Clear and specific feedback with examples where possible
+- Acknowledging when you are wrong or do not know something
+- Staying on topic in issues and pull requests
+
+Unacceptable behavior:
+
+- Personal attacks, insults, or harassment
+- Sustained off-topic disruption
+- Publishing private information without consent
+
+## Scope
+
+This applies to all project spaces: GitHub issues, pull requests, discussions, and any other venue where project work happens.
+
+## Enforcement
+
+The project maintainer handles violations. Contact: aric.camarata@gmail.com.
+
+Reports are reviewed promptly. Responses range from a private note to a permanent ban, depending on severity and history.
+
+## Attribution
+
+This code of conduct is adapted from the [Contributor Covenant](https://www.contributor-covenant.org), version 2.1.

.github/wiki/Contributing.md

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+# Contributing
+
+## Prerequisites
+
+- Node.js 20 or later
+- pnpm (enabled via corepack: `corepack enable`)
+
+## Setup
+
+```sh
+git clone https://github.com/acamarata/hijri-core.git
+cd hijri-core
+pnpm install
+```
+
+## Development
+
+```sh
+pnpm build          # compile TypeScript
+pnpm test           # build + run test suite
+pnpm run typecheck  # type-check without emitting
+pnpm run lint       # ESLint
+pnpm run format     # Prettier format
+```
+
+## Conversion Engines
+
+The package ships two engines:
+
+- **UAQ** (Umm al-Qura): table-based, identical to the official Saudi calendar
+- **FCNA**: an algorithmic engine for Fiqh Council of North America calculations
+
+When modifying either engine, cross-validate against the reference tables in the test suite. The UAQ table covers 1318-1500 AH; the FCNA engine is unbounded but less authoritative outside that range.
+
+## Downstream Packages
+
+hijri-core is the foundation for several thin wrapper packages:
+
+- `luxon-hijri`, `date-fns-hijri`, `dayjs-hijri-plus`, `moment-hijri-plus`, `temporal-hijri` (JS)
+- `hijri_core` (Dart)
+
+Breaking changes here require coordinated updates across all downstream packages. When changing the public API, note which downstream packages are affected in your PR description.
+
+## Pull Requests
+
+- One logical change per PR
+- Include tests with cross-validation against known dates
+- Update `CHANGELOG.md` under `[Unreleased]`
+- Do not bump the version number

.github/wiki/SECURITY.md

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+# Security Policy
+
+## Supported Versions
+
+| Version | Supported |
+| --- | --- |
+| 1.x | Yes |
+
+## Reporting a Vulnerability
+
+Do not open a public GitHub issue for security vulnerabilities.
+
+Email: aric.camarata@gmail.com
+
+Include:
+
+- A description of the vulnerability
+- Steps to reproduce
+- Potential impact
+- Any suggested fix, if you have one
+
+You will receive an acknowledgment within 48 hours and a resolution timeline within 7 days.
+
+## Scope
+
+This package is a pure computation library. It performs no network requests, reads no files, and holds no credentials. All calendar conversion logic is deterministic arithmetic. The primary security concern would be a supply-chain compromise of the npm package.

.github/wiki/_Footer.md

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+[npm](https://www.npmjs.com/package/hijri-core) · [GitHub](https://github.com/acamarata/hijri-core) · [Changelog](https://github.com/acamarata/hijri-core/blob/main/CHANGELOG.md) · MIT License

.github/wiki/_Sidebar.md

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+## hijri-core
+
+**[Home](Home)**
+
+**Reference**
+- [API Reference](API-Reference)
+- [Architecture](Architecture)
+
+**Contributing**
+- [Contributing](Contributing)
+- [Code of Conduct](CODE_OF_CONDUCT)
+- [Security](SECURITY)
+
+**Links**
+- [npm](https://www.npmjs.com/package/hijri-core)
+- [GitHub](https://github.com/acamarata/hijri-core)
+- [Changelog](https://github.com/acamarata/hijri-core/blob/main/CHANGELOG.md)