feat(schema): refine and expand extension metadata schema

- Introduce `scope`, `tags`, `min_version`, `homepage`, and `installation` fields for enhanced discoverability and guidance.
- Remove `install` and `compatibility` objects, replacing them with a simplified `installation` string field.
- Add `examples/` directory with full exemplar files for each extension type.
- Update `schema-design.md` to reflect new schema, clarify field definitions, and improve documentation structure.

data/schema.json

@@ -8,64 +8,56 @@
     "name": {
       "type": "string",
       "minLength": 1,
-      "description": "Name of the project or tool"
+      "description": "Display name of the project or tool"
     },
     "repo": {
       "type": "string",
       "format": "uri",
-      "description": "URL to the repository"
+      "description": "URL to the repository (https://github.com/...)"
     },
-"tagline": {
+    "tagline": {
       "type": "string",
       "minLength": 1,
       "maxLength": 120,
-      "description": "Short punchy summary of the project (shown in collapsed view)"
+      "description": "Short punchy summary (shown in collapsed view)"
     },
     "description": {
       "type": "string",
       "minLength": 1,
       "description": "Full description of the project (shown when expanded)"
     },
-    "install": {
-      "type": "object",
-      "description": "Installation instructions",
-      "properties": {
-        "type": {
-          "type": "string",
-          "enum": ["config", "npm", "pip", "go", "script", "manual"],
-          "description": "Type of installation method"
-        }
+    "scope": {
+      "type": "array",
+      "items": {
+        "type": "string",
+        "enum": ["global", "project"]
       },
-      "required": ["type"],
-      "additionalProperties": false
-    },
-    "compatibility": {
-      "type": "object",
-      "description": "Compatibility information",
-      "properties": {
-        "platforms": {
-          "type": "array",
-          "items": {
-            "type": "string"
-          },
-          "description": "Supported platforms"
-        },
-        "opencode": {
-          "type": "string",
-          "description": "Compatible Opencode version"
-        }
-      },
-      "required": ["platforms", "opencode"],
-      "additionalProperties": false
+      "minItems": 1,
+      "uniqueItems": true,
+      "description": "Installation scope: global (~/.config/opencode/) or project (.opencode/). Defaults to [global] if omitted."
     },
     "tags": {
       "type": "array",
       "items": {
         "type": "string"
       },
-      "description": "Tags for categorization"
+      "description": "Tags for filtering and discoverability"
+    },
+    "min_version": {
+      "type": "string",
+      "pattern": "^[0-9]+\\.[0-9]+\\.[0-9]+",
+      "description": "Minimum OpenCode version required (semver format, e.g. '1.0.0')"
+    },
+    "homepage": {
+      "type": "string",
+      "format": "uri",
+      "description": "Documentation URL if different from repository"
+    },
+    "installation": {
+      "type": "string",
+      "description": "Detailed installation instructions in markdown format"
     }
   },
   "required": ["name", "repo", "tagline", "description"],
-  "additionalProperties": false
+  "additionalProperties": true
 }