feat: comprehensive registry improvements

Community docs:
- CODE_OF_CONDUCT.md (Contributor Covenant v2.1)
- SECURITY.md (vulnerability reporting policy)
- CHANGELOG.md (initial release notes)
- CODEOWNERS (per-type review ownership)

GitHub config:
- Issue templates: bug-report, pricing-correction, documentation
- FUNDING.yml (GitHub Sponsors)

Validation enhancements:
- Cross-reference check: hand [[requires]] → integration existence
- Routing alias collisions as warnings (errors with --strict)
- --strict flag to promote warnings to errors
- --type filter to validate single content type
- CI: add taplo format check and lychee link check jobs

Developer experience:
- Makefile with validate, fmt, and scaffold targets
- Scaffold templates for all 5 content types
- .pre-commit-config.yaml (trailing whitespace, TOML check, validate)
- docs/content-guide.md (naming, descriptions, prompts, decision guide)

Content quality:
- schema.toml: add last_verified field for model pricing
- CONTRIBUTING.md: add pricing verification guide with source links

CHANGELOG.md

@@ -0,0 +1,23 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/).
+
+## [Unreleased]
+
+## [1.0.0] - 2026-03-21
+
+### Added
+
+- 46 LLM providers with 220+ model definitions
+- 33 agent definitions across diverse domains
+- 14 hand definitions (communication, content, data, development, productivity)
+- 25 MCP integration templates
+- 2 skill examples (prompt-only and Python)
+- 1 plugin example (echo-memory)
+- Validation script with per-type and cross-type checks
+- CI workflow for automated validation
+- README documentation for every directory and subdirectory
+- CONTRIBUTING guide with per-type examples and checklists
+- Schema reference (schema.toml)