Add website release notes with AI-powered generation pipeline

.agents/skills/release-notes/SKILL.md

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+---
+name: release-notes
+description: >
+  Generate or regenerate polished website release notes for SkiaSharp versions.
+  Fetches raw release data from GitHub, reads the template, and writes formatted
+  markdown pages to documentation/docfx/releases/.
+
+  Use this skill whenever the user asks to:
+  - Generate release notes for a version ("write release notes for 3.119.2")
+  - Regenerate or refresh release notes ("regenerate 3.119.x release notes")
+  - Format raw release data into the website template
+  - Update the release notes after publishing a new release
+
+  Triggers: "release notes for X", "regenerate release notes", "format release notes",
+  "update website release notes", "write release notes", "refresh release notes".
+
+  This skill is also called by the release-publish skill (Step 7) after annotating
+  a GitHub release. You don't need to be asked explicitly — if release-publish is
+  running and reaches Step 7, invoke this skill.
+---
+
+# Release Notes Skill
+
+Generate polished website release notes for one or more SkiaSharp versions.
+
+## Process
+
+### Step 1 — Determine versions
+
+Ask the user which version(s) to generate, or infer from context:
+- A specific version: `3.119.2`
+- Multiple versions: `3.119.0, 3.119.1, 3.119.2`
+- A range by minor: "all 3.119.x" — list files matching `documentation/docfx/releases/3.119.*.md`
+  and also check GitHub for any releases not yet on disk
+- If called from release-publish, the version is already known
+
+### Step 2 — Fetch raw data
+
+For each version, fetch the raw GitHub release data:
+
+```bash
+python3 .agents/skills/release-notes/scripts/generate-release-notes.py --version {X.Y.Z}
+```
+
+This outputs raw markdown to a temp directory. Multiple `--version` flags can be
+combined in one call. Read the output file(s) from the temp directory.
+
+### Step 3 — Read the template
+
+Read `documentation/docfx/releases/TEMPLATE.md`. This is a real example of a polished
+release notes page. Match its structure, tone, and formatting exactly.
+
+Determine each version's status from its raw data:
+- **Stable release**: has a "## Stable Release" section → header uses `Released {date}` + NuGet link + GitHub Release link
+- **Preview only**: only preview sections → header uses `Preview only` + NuGet preview link + GitHub Release link
+
+### Step 4 — Write polished pages
+
+For each version, write `documentation/docfx/releases/{X.Y.Z}.md` with polished content.
+If the file exists, replace its entire content — this is a full regeneration.
+
+Follow these rules:
+
+1. **Highlights** — 1-3 sentences. What's the story? Lead with the biggest changes.
+   Mention community contributors by linked name.
+
+2. **Skia engine** — If a "Bump skia" or "milestone" PR appears in the raw data,
+   list it first under an **Engine** category.
+
+3. **Categorize features** — Group by what they affect. Use sub-headers:
+   Engine, GPU & Rendering, API Surface, Text & Fonts, Platform, Security, etc.
+   Each item: **bold title** — description. ❤️ [@contributor](https://github.com/contributor) ([#NNN](url))
+
+4. **Community contributors** — Anyone not @mattleibow. Mark with ❤️ inline AND
+   in a Contributors table. **ALWAYS** link: `[@user](https://github.com/user)`.
+   Never write bare `@user` anywhere in the file.
+
+5. **Omit noise** — Skip version bumps, CI-only fixes, doc updates, workflow/skill changes.
+   If many, mention as: "Plus several CI and documentation improvements."
+
+6. **Breaking changes** — If any, list under `### ⚠️ Breaking Changes` after Highlights.
+
+7. **PR links** — Every item links to its PR.
+
+8. **Rollup at top** — Aggregate ALL changes across all previews into the main sections.
+
+9. **Previews are minimal** — One sentence + changelog link each, at the bottom.
+
+10. **Links section** — Full Changelog, NuGet Package, API Diff.
+
+### Step 5 — Update TOC and index
+
+After writing all version files:
+
+```bash
+python3 .agents/skills/release-notes/scripts/generate-release-notes.py --update-toc
+```
+
+## Parallelization
+
+When regenerating multiple versions, process them in parallel — each version is independent.
+Fetch all raw data in one script call, then launch one agent per version to write the polished page.