feat: JSON Schema validation for metadata.yaml as pre-commit hook

Adds schema/metadata.json (JSON Schema draft-07) as the authoritative
schema for all rpms/*/metadata.yaml files.  Key constraints:

- additionalProperties: false at both the top level and builds items,
  so unknown fields are rejected outright
- name allows dots (fixes neovim-glibc-2.17)
- github is optional (fixes claude-code, which has no GitHub repo)
- repository enum includes fedora/42, fedora/43, fedora/44
- dist_tag boolean field documented in schema

Pre-commit hook (check-jsonschema 0.37.2) runs against every file
matching ^rpms/[^/]+/metadata\.yaml$ on every commit.

Also fixes rpms/claude-code/metadata.yaml: removes the unknown
claude_ai field and normalises field order.

.pre-commit-config.yaml

@@ -31,6 +31,14 @@ repos:
             "-s",
           ]
 
+  - repo: https://github.com/python-jsonschema/check-jsonschema
+    rev: 0.37.2
+    hooks:
+      - id: check-jsonschema
+        name: Validate RPM package metadata
+        files: ^rpms/[^/]+/metadata\.yaml$
+        args: [--schemafile, schema/metadata.json]
+
   - repo: https://github.com/astral-sh/ruff-pre-commit
     rev: v0.14.7
     hooks:

rpms/claude-code/metadata.yaml

@@ -1,19 +1,18 @@
-arch: amd64
-builds:
-- image: git.unkin.net/unkin/almalinux8-rpmbuilder:latest
-  release: 1
-  repository:
-  - almalinux/el8
-  version: 2.1.126
-- image: git.unkin.net/unkin/almalinux9-rpmbuilder:latest
-  release: 1
-  repository:
-  - almalinux/el9
-  version: 2.1.126
-claude_ai: true
+name: claude-code
 description: Claude Code - Anthropic's agentic AI coding tool
+arch: amd64
+platform: linux
+maintainer: Anthropic
 homepage: https://claude.ai/code
 license: Proprietary
-maintainer: Anthropic
-name: claude-code
-platform: linux
+builds:
+- repository:
+  - almalinux/el8
+  image: git.unkin.net/unkin/almalinux8-rpmbuilder:latest
+  release: 1
+  version: 2.1.126
+- repository:
+  - almalinux/el9
+  image: git.unkin.net/unkin/almalinux9-rpmbuilder:latest
+  release: 1
+  version: 2.1.126

schema/metadata.json

@@ -0,0 +1,111 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "additionalProperties": false,
+  "description": "Schema for rpms/*/metadata.yaml files",
+  "properties": {
+    "arch": {
+      "enum": [
+        "amd64",
+        "arm64",
+        "x86_64"
+      ],
+      "type": "string"
+    },
+    "builds": {
+      "items": {
+        "additionalProperties": false,
+        "properties": {
+          "image": {
+            "minLength": 1,
+            "pattern": "^[a-zA-Z0-9][a-zA-Z0-9\\-_.:/@]+$",
+            "type": "string"
+          },
+          "release": {
+            "oneOf": [
+              {
+                "minLength": 1,
+                "type": "string"
+              },
+              {
+                "type": "number"
+              }
+            ]
+          },
+          "repository": {
+            "items": {
+              "enum": [
+                "almalinux/el8",
+                "almalinux/el9",
+                "fedora/42",
+                "fedora/43",
+                "fedora/44"
+              ],
+              "type": "string"
+            },
+            "minItems": 1,
+            "type": "array"
+          },
+          "version": {
+            "minLength": 1,
+            "pattern": "^[0-9]+(\\.[0-9]+)*(-[a-zA-Z0-9]+)*$",
+            "type": "string"
+          }
+        },
+        "required": [
+          "repository",
+          "image",
+          "release",
+          "version"
+        ],
+        "type": "object"
+      },
+      "minItems": 1,
+      "type": "array"
+    },
+    "description": {
+      "minLength": 1,
+      "type": "string"
+    },
+    "dist_tag": {
+      "type": "boolean"
+    },
+    "github": {
+      "minLength": 1,
+      "pattern": "^[a-zA-Z0-9\\-_]+/[a-zA-Z0-9\\-_.]+$",
+      "type": "string"
+    },
+    "github_release_pattern": {
+      "minLength": 1,
+      "type": "string"
+    },
+    "homepage": {
+      "minLength": 1,
+      "pattern": "^https?://.+",
+      "type": "string"
+    },
+    "license": {
+      "minLength": 1,
+      "type": "string"
+    },
+    "maintainer": {
+      "minLength": 1,
+      "type": "string"
+    },
+    "name": {
+      "minLength": 1,
+      "pattern": "^[a-zA-Z0-9][a-zA-Z0-9\\-_.]*$",
+      "type": "string"
+    },
+    "platform": {
+      "minLength": 1,
+      "type": "string"
+    }
+  },
+  "required": [
+    "name",
+    "description",
+    "builds"
+  ],
+  "title": "RPM Package Metadata",
+  "type": "object"
+}