chore: add Claude Code configuration (#236)

* chore: add Claude Code configuration

Add CLAUDE.md with project-specific guidance for Claude Code including:
- Build commands for Maven operations
- Architecture overview with key packages
- Documentation of OSCAL-specific Metapath functions
- Code style conventions
- Git workflow and worktree requirements
- Testing requirements

Also adds settings.json for Claude Code plugins configuration.

* fix: format bare URL as Markdown link in CLAUDE.md

Author: david-waltermire

.claude/CLAUDE.md

@@ -0,0 +1,137 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Build Commands
+
+```bash
+# Build and install
+mvn install
+
+# Replicate CI/CD build (recommended before pushing)
+mvn install -PCI -Prelease
+
+# Run tests only
+mvn test
+
+# Run a single test class
+mvn test -Dtest=ExamplesTest
+
+# Run a single test method
+mvn test -Dtest=ExamplesTest#testExample
+
+# Skip tests during build
+mvn install -DskipTests
+
+# Check license headers
+mvn license:check
+
+# Auto-format source code
+mvn formatter:format
+
+# Check for Checkstyle issues
+mvn checkstyle:check
+```
+
+## Project Overview
+
+liboscal-java is a Java library for processing [OSCAL](https://pages.nist.gov/OSCAL/) content. It provides:
+
+- Reading/writing OSCAL documents in XML, JSON, and YAML formats
+- OSCAL profile resolution to produce resolved catalogs
+- Validation of OSCAL content well-formedness and syntax
+- Experimental Metaschema constraint validation
+- Builders for programmatically creating OSCAL data elements
+
+This library is built on the [Metaschema Java Tools](https://github.com/metaschema-framework/metaschema-java) project.
+
+## Architecture
+
+This is a single-module Maven project. Key packages:
+
+- `dev.metaschema.oscal.lib` - Core library classes including `OscalBindingContext`
+- `dev.metaschema.oscal.lib.model` - Generated OSCAL model classes (Catalog, Profile, SSP, etc.)
+- `dev.metaschema.oscal.lib.profile.resolver` - Profile resolution implementation
+- `dev.metaschema.oscal.lib.metapath.function.library` - OSCAL-specific Metapath functions
+
+### Generated Model Classes
+
+OSCAL model classes are generated from Metaschema definitions in the `oscal/` submodule during the build. These appear in `target/generated-sources/metaschema/` and include classes like `Catalog`, `Profile`, `SystemSecurityPlan`, `ComponentDefinition`, etc. Abstract base classes in `dev.metaschema.oscal.lib.model` provide common functionality.
+
+### OSCAL-Specific Metapath Functions
+
+Custom functions beyond core Metaschema (registered in `OscalFunctionLibrary`):
+- `has-oscal-namespace` - Check OSCAL namespace membership
+- `resolve-profile` - Resolve an OSCAL profile to a catalog
+- `resolve-reference` - Resolve OSCAL internal references
+
+## Code Style
+
+- Java 11 target
+- Uses SpotBugs annotations (`@NonNull`, `@Nullable`) for null safety
+- Package structure follows `dev.metaschema.oscal.*` convention
+
+## Git Workflow
+
+- Repository: <https://github.com/metaschema-framework/liboscal-java>
+- **All PRs MUST be created from a personal fork** (required by CONTRIBUTING.md)
+- **All PRs MUST target the `develop` branch**
+- All changes require PR review
+
+## Git Worktrees (MANDATORY)
+
+**All development work MUST be done in a git worktree, not in the main repository checkout.**
+
+### Why Worktrees Are Required
+
+- Isolates feature work from the main checkout
+- Prevents accidental commits to the wrong branch
+- Allows parallel work on multiple features
+- Keeps the main checkout clean for reference and review
+
+### Worktree Location
+
+Worktrees are stored in `.worktrees/` directory (gitignored) relative to the repository root.
+
+### Workflow
+
+1. **Before starting any feature work**, create a worktree:
+
+```bash
+# Create worktree for a new feature branch
+git worktree add .worktrees/<feature-name> -b <feature-branch> origin/develop
+```
+
+2. **Check for existing worktrees** before making changes:
+
+```bash
+git worktree list
+```
+
+3. **Switch to the appropriate worktree** if one already exists for your task
+
+4. **Remove worktrees** after PRs are merged:
+
+```bash
+git worktree remove .worktrees/<feature-name>
+```
+
+### Red Flags (You're Working in the Wrong Directory)
+
+- Making changes without first checking `git worktree list`
+- Working in the main repository when a worktree exists for the feature
+- Creating files or commits in the main checkout for feature work
+
+Use the `superpowers:using-git-worktrees` skill for guided worktree creation and management.
+
+## Testing
+
+- Tests use JUnit 5
+- All PRs require passing CI checks before merge
+- 100% of unit tests must pass before pushing code
+
+## Dependencies
+
+This library depends on:
+- `metaschema-java` (core Metaschema framework)
+- OSCAL model bindings (generated from OSCAL Metaschema modules in `oscal/` submodule)

.claude/settings.json

@@ -0,0 +1,24 @@
+{
+  "extraKnownMarketplaces": {
+    "metaschema-framework": {
+      "source": {
+        "source": "github",
+        "repo": "metaschema-framework/claude-plugins"
+      }
+    },
+    "superpowers-marketplace": {
+      "source": {
+        "source": "github",
+        "repo": "obra/superpowers"
+      }
+    }
+  },
+  "enabledPlugins": {
+    "metaschema@metaschema-framework": true,
+    "metaschema-tools@metaschema-framework": true,
+    "oscal@metaschema-framework": true,
+    "oscal-tools@metaschema-framework": true,
+    "dev-metaschema@metaschema-framework": true,
+    "superpowers@superpowers-marketplace": true
+  }
+}