Edit command (web UI), docs, and CodeGuardian agent skill

[aroff]

This PR includes the full implementation: edit server, React edit-ui, docs, and agent skill.

Edit command and rule editor

• codeguardian edit [file]: local server (default port 3847) and web UI to edit a single rule file; default file .codeguardian/development-rules.cg.yaml
• Options: --port, --host, --no-open
• Form-based editing for rule id, description, and full rule tree (combinators, selectors, assertions)
• Tooltips and hints on fields (path pattern, exclude pattern, status, message, suggestion, etc.)
• Open: load another rule file (GET/PUT /api/rule with optional file path)
• Validate: POST /api/validate to check rule parses and builds
• View YAML: full serialization including assertion properties
• Save / Revert

Docs

• README: Rule Editor feature bullet, "Editing rules (web UI)" section, CLI reference for codeguardian edit, Rule editor doc link, Current Features
• Cheat_Sheet: "Editing rules in the browser" subsection, "Message and Suggestion" under Assertions
• CHANGELOG: [0.1.0-beta.10] entry (edit command, Open, Validate, View YAML, tooltips; View YAML fix)

Agent skill

• New skill/ with SKILL.md, skill-project.toml, references/cli.md, references/dsl.md, README.md
• CodeGuardian basics, CLI usage, and DSL reference for rule authoring