docs: add Claude Code instructions

.claude/CLAUDE.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Overview
+
+This is `mll-lab/php-utils`, a PHP library of shared utilities for MLL (Munich Leukemia Laboratory).
+It provides domain-specific utilities for laboratory automation equipment, sample sheets, microplates, and general PHP helpers.
+
+## Commands
+
+```bash
+make setup     # Install dependencies (runs composer update/validate/normalize)
+make it        # Run commonly used targets: fix, stan, test
+make fix       # Format code (rector + php-cs-fixer)
+make stan      # Static analysis with PHPStan (level max)
+make test      # Run PHPUnit tests
+make coverage  # Run tests with code coverage
+```
+
+Run a single test:
+```bash
+vendor/bin/phpunit tests/BavarianHolidaysTest.php
+vendor/bin/phpunit --filter testNameHoliday
+```
+
+## Release Process
+
+This project uses [semantic-release](https://semantic-release.gitbook.io) for automated versioning and releases.
+Releases are triggered automatically when commits are pushed to `master`.
+
+### Commit Message Format
+
+Commits must follow [Conventional Commits](https://www.conventionalcommits.org):
+- `feat: add new feature` - triggers minor version bump (e.g., 5.23.0 → 5.24.0)
+- `fix: correct bug` - triggers patch version bump (e.g., 5.23.0 → 5.23.1)
+- `feat!:` or `BREAKING CHANGE:` in footer - triggers major version bump
+
+PR titles are validated against this format by CI.
+The CHANGELOG.md is automatically generated from commit messages.
+
+### Scope Examples
+
+Use scope to clarify the area of change:
+- `feat(phpstan): add new rule` - PHPStan-related feature
+- `fix(microplate): correct coordinate calculation` - Microplate module fix
+
+## Architecture
+
+### Domain Modules
+
+- **Microplate** (`src/Microplate`) - Generic coordinate system for laboratory microplates (96-well, 48-well, etc.)
+  - `CoordinateSystem` - Abstract base defining rows/columns (e.g., `CoordinateSystem12x8` for 96-well plates)
+  - `Coordinates` - Represents a position like "A1" with row/column
+  - `Microplate` - Generic container mapping coordinates to well contents
+  - `Section` / `SectionedMicroplate` - Subdivide plates into logical regions
+  - `MicroplateSet` - Work with multiple plates as a unit (AB, ABCD, ABCDE variants)
+
+- **Tecan** (`src/Tecan`) - Generate pipetting instructions for Tecan liquid handling robots (GWL format)
+  - `BasicCommands` - Low-level commands: Aspirate, Dispense, Wash, etc.
+  - `CustomCommands` - Higher-level compound operations
+  - `Rack` - Predefined rack types (FluidXRack, DestPCR, etc.)
+  - `TecanProtocol` - Builds complete protocol files
+
+- **IlluminaSampleSheet** (`src/IlluminaSampleSheet`) - Generate sample sheets for Illumina sequencers
+  - `V1` - Classic format (MiSeq, NextSeq, etc.)
+  - `V2` - NovaSeq X format with BCL Convert sections
+
+- **LightcyclerSampleSheet** (`src/LightcyclerSampleSheet`) - Sample sheets for Roche LightCycler qPCR
+
+- **FluidXPlate** (`src/FluidXPlate`) - FluidX tube rack scanning and barcode validation
+
+- **TecanScanner** (`src/TecanScanner`) - Parse Tecan scanner output files
+
+- **Qiaxcel** (`src/Qiaxcel`) - Import Qiagen Qiaxcel capillary electrophoresis data
+
+### General Utilities
+
+- `BavarianHolidays` - Bavarian holiday calendar with business day calculations
+- `StringUtil`, `Number`, `CSVArray` - Common helpers
+- `Specification` - Specification pattern implementation
+
+### PHPStan Extension
+
+Custom PHPStan rules in `src/PHPStan/Rules`:
+- `IdToIDRule` and variants - Enforce "ID" capitalization (not "Id") in variable names, method names, class names, property names
+- `MissingClosureParameterTypehintRule` - Require closure parameter type hints
+- `ThrowableClassNameRule` - Naming conventions for exception classes
+
+Rules are configured in `rules.neon` and `extension.neon`.
+
+## Conventions
+
+### ID Capitalization
+
+Use "ID" not "Id" in names: `$userID`, `getUserID()`, `SampleID` (not `$userId`, `getUserId()`, `SampleId`).
+PHPStan rules enforce this.
+
+### Coordinate System Naming
+
+Name coordinate systems by dimensions: `CoordinateSystem12x8` (12 columns × 8 rows = 96 wells), not by total positions.
+
+### Tests
+
+Tests mirror the `src` structure under `tests`.
+Use PHPUnit attributes for data providers: `#[DataProvider('dataProviderName')]`.

.claude/settings.json

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+{
+  "permissions": {
+    "allow": [
+      "Bash(make fix:*)",
+      "Bash(make stan:*)",
+      "Bash(make test:*)"
+    ],
+    "deny": [],
+    "ask": []
+  }
+}