Add a skill instructing claude on how to format code

.config/skills/format-code/SKILL.md

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+---
+name: format-code
+description: Formats the codebase using nightly rustfmt. Use when asked to "format the code", "run rustfmt", "cargo fmt", or when formatting is needed after code changes.
+context: root
+user-invocable: true
+---
+
+# Format Code
+
+## Description
+Formats all Rust code in the codebase using nightly rustfmt to ensure consistent code style. This skill always uses nightly rustfmt to access the latest formatting features and configurations.
+
+## When to Use
+- When asked to "format the code" or "format my code"
+- When asked to "run rustfmt" or "cargo fmt"
+- When asked to "fix formatting" or "clean up formatting"
+- After completing code changes that need formatting
+- Before committing changes to ensure consistent style
+- When formatting issues are flagged by CI or pre-commit hooks
+
+## How It Works
+
+### Step 1: Run Nightly Rustfmt
+Execute the format command using nightly toolchain:
+
+```bash
+cargo +nightly fmt
+```
+
+This formats all Rust files in the workspace according to the project's `rustfmt.toml` configuration (if present).
+
+### Step 2: Report Results
+After formatting completes:
+- If changes were made, inform the user that files were formatted
+- If no changes were needed, confirm the code was already properly formatted
+- Report any errors that occurred during formatting
+
+## Example Usage
+
+**User Request:** "Format the code"
+
+**Expected Behavior:**
+
+1. **Run formatter**:
+   ```bash
+   cargo +nightly fmt
+   ```
+
+2. **Check for changes** (optional):
+   ```bash
+   git status
+   ```
+
+3. **Report**:
+   ```
+   Code formatted successfully using nightly rustfmt.
+   ```
+
+**User Request:** "Run rustfmt before I commit"
+
+**Expected Behavior:**
+
+1. **Run formatter**:
+   ```bash
+   cargo +nightly fmt
+   ```
+
+2. **Report**:
+   ```
+   Formatting complete. Ready to commit.
+   ```
+
+## Best Practices
+
+### Do:
+- Always use `cargo +nightly fmt` to ensure nightly toolchain
+- Run formatting before committing changes
+- Report whether any files were modified by the formatter
+
+### Don't:
+- Use `cargo fmt` without the `+nightly` flag
+- Skip formatting when making code changes
+- Ignore formatting errors
+
+## Quality Checklist
+
+Before considering the task complete, verify:
+- [ ] Ran `cargo +nightly fmt` successfully
+- [ ] No formatting errors were reported
+- [ ] User is informed of the result
+
+## Troubleshooting
+
+**Nightly toolchain not installed:**
+- Run `rustup install nightly` to install
+- Then retry the format command
+
+**Formatting fails with parse errors:**
+- Check for syntax errors in the Rust code
+- Fix compilation errors first, then format
+
+**rustfmt.toml issues:**
+- Verify the configuration file is valid
+- Check that nightly-only options are supported
+
+## Related Skills
+- `create-git-commit` - Create commits after formatting
+- Code quality and linting workflows