Add Copilot instructions for repository

.github/copilot-instructions.md

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+# Copilot Instructions for release-data
+
+This repository provides release data for the [endoflife.date](https://endoflife.date) website. Scripts scrape release information from various sources and output structured JSON files.
+
+## Build, Test, and Lint
+
+**Install dependencies:**
+```bash
+pip install -r requirements.txt
+```
+
+**Lint code:**
+```bash
+pre-commit run --all-files
+```
+
+**Update all products:**
+```bash
+python update-release-data.py -v -p '../endoflife.date/products'
+```
+
+**Update a single product:**
+```bash
+python update-release-data.py -v -p '../endoflife.date/products' python
+```
+
+**Generate automation report:**
+```bash
+python report.py -p '../endoflife.date/products'
+```
+
+## Architecture
+
+### Data Flow
+
+1. **Product definitions** live in the [endoflife.date repository](https://github.com/endoflife-date/endoflife.date) (`products/*.md` files with YAML frontmatter)
+2. **Scraper scripts** (`src/*.py`) fetch release data from various sources (Git tags, GitHub releases, APIs, HTML scraping)
+3. **Output** goes to `releases/*.json` files with versioned release dates
+4. **GitHub Actions** runs updates 4x daily and commits changes automatically
+
+### Core Components
+
+**`src/common/`** - Shared utilities:
+- `endoflife.py`: Parses product frontmatter, handles `auto` config (regex patterns, version templates)
+- `releasedata.py`: Manages `releases/*.json` files via `ProductData` context manager
+- `dates.py`: Date/time utilities
+- `git.py`, `github.py`, `http.py`: Source-specific helpers
+
+**Scraper scripts** (`src/*.py`):
+- Each script is standalone and rebuilds data from scratch (never relies on existing JSON)
+- Uses `ProductData` context manager that auto-saves on success or raises `ProductUpdateError` on failure
+- Filters versions via `config.first_match(version_str)` and renders via `config.render(match)`
+
+**Main orchestrator** (`update-release-data.py`):
+- Reads product frontmatter from website repo
+- Executes relevant scripts for each product
+- Tracks execution times and failures
+- Outputs GitHub Actions summary
+
+## Key Conventions
+
+### Product Frontmatter Auto Config
+
+Products define automation in YAML frontmatter:
+```yaml
+auto:
+  methods:
+    - git: https://github.com/example/repo
+      regex: '^v?(?P<major>[0-9]+)\.(?P<minor>[0-9]+)\.(?P<patch>[0-9]+)$'
+      template: '{{major}}.{{minor}}.{{patch}}'
+```
+
+- **method**: Determines which `src/{method}.py` script runs
+- **regex**: Filters version strings (can be list for multiple patterns)
+- **regex_exclude**: Excludes matched versions
+- **template**: Liquid template to render version names from regex groups
+
+### Script Patterns
+
+All scripts follow this structure:
+```python
+from common.releasedata import ProductData, config_from_argv
+
+config = config_from_argv()
+with ProductData(config.product) as product_data:
+    for version_str in fetch_versions_from_source():
+        match = config.first_match(version_str)
+        if match:
+            version = config.render(match)
+            product_data.declare_version(version, release_date)
+```
+
+The `ProductData` context manager:
+- Automatically loads existing data on `__enter__`
+- Validates updates occurred (raises error if `updated=False`)
+- Saves sorted JSON on `__exit__`
+- Handles errors by reverting changes
+
+### Version Handling
+
+- **Stable only**: No beta, RC, nightly versions
+- **Dates**: YYYY-MM-DD format, preferably in release's timezone
+- **Sorting**: Versions sorted by (date, name) descending; releases sorted by name descending
+- **Identifiers**: Use `endoflife.to_identifier()` for consistent naming
+
+### JSON Output Format
+
+```json
+{
+  "releases": {
+    "1.2": {
+      "name": "1.2",
+      "releaseDate": "2024-01-15",
+      "releaseLabel": "optional-label",
+      "eol": "2025-01-15",
+      "eoas": "2024-07-15",
+      "eoes": "2024-10-15"
+    }
+  },
+  "versions": {
+    "1.2.3": {
+      "name": "1.2.3",
+      "date": "2024-01-15"
+    }
+  }
+}
+```
+
+- **releases**: Lifecycle data (EOL dates) - coarser-grained
+- **versions**: Point release dates - finer-grained
+
+### Cumulative Updates
+
+If `auto.cumulative: true` in frontmatter:
+- Script should **not** delete existing data before running
+- New data is merged with existing data
+- Used when multiple scripts contribute to the same product
+
+### Guiding Principles
+
+1. Scripts must be standalone and simple
+2. Never rely on existing data - rebuild from scratch each run
+3. Code should handle upstream changes gracefully
+4. Everything runs on GitHub Actions (no local state dependencies)