feat(astro-seo-graph)!: drop Astro 5, require Astro 6 + zod 4

.changeset/astro-seo-graph-2-0.md

@@ -0,0 +1,23 @@
+---
+'@jdevalk/astro-seo-graph': major
+---
+
+**Breaking:** drop Astro 5 from peer deps; require Astro 6 and zod 4.
+
+Why: Astro 5.x ships zod 3 and Astro 6.x ships zod 4. Supporting both Astro majors meant shipping zod 3 as a runtime dep while users on Astro 6 had zod 4 from `astro:content`. zod brands schemas with version-specific symbols, so `seoSchema(image)` (returned as a zod 3 schema) couldn't compose cleanly into a user's `z.object({ ... })` from `astro:content` (zod 4) — composition produced TS type errors and worked at runtime only by accident.
+
+**What changed:**
+
+- `peerDependencies.astro` is now `^6.0.0` (was `^5.0.0 || ^6.0.0`).
+- `dependencies.zod` is now `^4.4.3` (was `^3.24.0`).
+
+**What didn't change:**
+
+- The exported API surface (`<Seo>`, `createSchemaEndpoint`, `createSchemaMap`, `createApiCatalog`, `createMarkdownEndpoint`, `createIndexNowKeyRoute`, `seoSchema`, `imageSchema`, `buildAlternateLinks`, `breadcrumbsFromUrl`, `gitLastmod`, `aggregate`, `renderLlmsTxt`, `renderMarkdownAlternate`, all types) — all unchanged.
+- Our zod usage is core surface only (`z.object`, `z.string`, `z.enum`, `.min`, `.max`, `.optional`, `.default`) — no zod 4-specific syntax.
+
+**Migration:**
+
+If you're already on Astro 6, install: `pnpm add @jdevalk/astro-seo-graph@2`. Your `seo` and `featureImage` collection fields will start composing without the silent type drift they had under 1.x.
+
+If you're still on Astro 5, stay on `@jdevalk/astro-seo-graph@1.4.1`. The 1.x line gets bug fixes only — no new features ship to it.

packages/astro-seo-graph/package.json

@@ -51,12 +51,12 @@
         "test": "vitest run"
     },
     "peerDependencies": {
-        "astro": "^5.0.0 || ^6.0.0"
+        "astro": "^6.0.0"
     },
     "dependencies": {
         "@jdevalk/seo-graph-core": "workspace:*",
         "schema-dts": "^2.0.0",
-        "zod": "^3.24.0"
+        "zod": "^4.4.3"
     },
     "devDependencies": {
         "@types/node": "^22.0.0",