docs: add usage and developer documentation

Add user and developer documentation plus Pagenary docsite publishing support.

Includes Getting Started, Developer Guide, API and MCP references, Pagenary tenant metadata, npm scripts for sync/build/check/serve, and validation coverage for the generated docsite.

Closes #102

docsite/t3mp3st-docs/content/developers.md

@@ -0,0 +1,22 @@
+---
+title: "Developers"
+summary: "Integrate, extend, and contribute to T3MP3ST."
+description: "Integrate, extend, and contribute to T3MP3ST."
+audience: ["operator", "developer", "maintainer"]
+category: "navigation"
+status: "current"
+source: "T3MP3ST repository"
+sourcePath: "generated:developers"
+updated: "2026-07-20"
+---
+# Developers
+
+Integrate, extend, and contribute to T3MP3ST.
+
+## Pages
+
+- [Developer Guide](#developer-guide) - Architecture, local development, scripts, extension points, and release checks.
+- [API Reference](#api-reference) - Local HTTP API endpoints grouped by workflow.
+- [MCP Guide](#mcp-guide) - Model Context Protocol setup and security_recon usage.
+- [Contribution Receipts](#contribution-receipts) - Evidence template for scoped pull requests and claim changes.
+- [Pull Request Delivery](#pull-request-delivery) - Contributor and maintainer checklist for reviewable pull requests.