Bootstrap repo with TypeScript source-of-truth and generated JSON Schema

Tracks SEP-2127 (MCP Server Cards) as an experimental extension while the SEP
itself is under review. The schema.ts is structured to be lifted directly into
schema/draft/schema.ts of the main spec when Server Cards graduate -- only the
inlined MetaObject and Icon definitions need to be removed during migration.

- schema.ts: ServerCard, Server, Repository, Remote, Package, Argument, Input,
  KeyValueInput, etc. plus inlined MetaObject and Icon
- scripts/generate-schema.ts: typescript-json-schema with 2020-12 transforms
- scripts/validate-examples.ts: ajv validator over examples/{ServerCard,Server}/
- examples/: 2 valid + 4 invalid Server Card cases, 1 valid Server case
- README: status, layout, schema URL conventions, graduation plan
- CI workflow: check + validate + format on every PR

tsconfig.json

@@ -0,0 +1,11 @@
+{
+  "compilerOptions": {
+    "noEmit": true,
+    "target": "es2016",
+    "rootDir": ".",
+    "forceConsistentCasingInFileNames": true,
+    "strict": true,
+    "skipLibCheck": true
+  },
+  "include": ["schema.ts"]
+}