Strict 0.4 schema still requires server.mcp_config for uv type (contradicts spec + loose schema; incomplete fix of #201)

[aosmcleod]

Summary

The strict 0.4 schema still requires server.mcp_config, which contradicts both MANIFEST.md and the loose schema for uv-type servers. This is the same failure as #201 (closed as completed) — but #201 was resolved by adding mcp_config to the hello-world-uv example, not by fixing the schema, so a spec-compliant UV extension without mcp_config still fails mcpb validate and mcpb pack.

Mechanism

• MANIFEST.md:432 (uv server type): "mcp_config is optional (host manages execution)".
• src/schemas_loose/0.4.ts:40: mcp_config: McpbManifestMcpConfigSchema.optional() (correct).
• src/schemas/0.4.ts:39: mcp_config: McpbManifestMcpConfigSchema — required.
• validateManifest (src/node/validate.ts) and pack (src/cli/pack.ts) use the strict schema, so a UV manifest with no mcp_config is rejected.

Reproduction (executed)

A manifest_version: "0.4" manifest with server: { type: "uv", entry_point: "main.py" } and no mcp_config:

• loose schema → success: true
• strict schema → success: false, server.mcp_config: Required

Suggested fix

Make it optional in the strict schema to match the loose schema + spec:

mcp_config: McpbManifestMcpConfigSchema.optional(),

Ideally enforce it as required only for non-uv server types via .superRefine, but at minimum it must be optional so UV extensions validate. (Refs #201.)

Environment: current main (70fe3b3).