Automated transformations applied via zod-v3-to-v4:
- String validators: z.string().url() → z.url()
- Number validators: z.number().int() → z.int()
- Object methods: .passthrough() → z.looseObject(), .strict() → z.strictObject()
- Schema composition: .merge() → .extend() where applicable
- Error messages: { message } → { error }
- Defaults: .default() → .prefault()
- Object stripping: .strip() removed/consolidated

Remove the external zod-to-json-schema library in preparation
for migrating to Zod v4's native toJSONSchema() method.

Replace zodToJsonSchema() calls with Zod v4's native z.toJSONSchema() method.
Use default options (JSON Schema Draft 2020-12) for simplicity and standard compliance.

Removed unnecessary options:
- target: 'openapi-3.0' - default draft-2020-12 is appropriate for MCP
- strictUnions: true - option doesn't exist in Zod v4's native implementation

Replace removed/renamed types with v4 equivalents:
- AnyZodObject → ZodObject<any>
- z.objectOutputType<> → z.infer<ZodObject<>>
- Remove ZodTypeDef import (will be addressed with PromptArgsRawShape fix)

This resolves 4 compilation errors (Category B & C).

Replace generic ZodType<string, ZodTypeDef, string> with concrete ZodString type.
This fixes compatibility with Zod v4's internal type system changes.

Resolves 8 compilation errors (Category D & F):
- 5 errors in mcp.ts type constraints
- 3 cascading errors in example servers

The previous class-based approach that extended ZodType no longer works in
Zod v4 due to architectural changes. This implements an immutable wrapper
approach that creates a new schema object with completion metadata while
preserving all validation behavior.

- Creates new schema via Object.create() + property copying
- Adds completion metadata to new _def object (not mutating shared state)
- Maintains _def === _zod.def invariant
- Preserves all schema properties including getters
- Follows Zod's immutability pattern

Also updates mcp.ts to check _def.typeName instead of instanceof.
All 755 tests pass.

Extracts the intersection type to a named CompletableSchema<T> type alias,
making the function signature more readable and reusable.

- Remove unused ZodTypeAny import
- Replace any with ZodRawShape in RegisteredTool interface
- Apply prettier formatting to modified files