refactor: consolidate schema validation under @socketsecurity/lib/schema

Remove the duplicate `@socketsecurity/lib/validation/validate-schema`
export, which shipped one release ago (5.20.0) as a single-file
validator + parser. The newer `@socketsecurity/lib/schema/*` split
(validate / parse / types, added 10c4077) supersedes it: identical
`validateSchema` / `parseSchema` signatures, better module layout,
dedicated `@socketsecurity/lib/schema/types` for the shared type
surface, and full test coverage.

Changes:
- `src/ipc.ts` — switch internal `parseSchema` import from
  `./validation/validate-schema` to `./schema/parse`.
- Delete `src/validation/validate-schema.ts` (267 LOC) and its test
  file. The sibling `src/validation/json-parser.ts` and
  `src/validation/types.ts` stay — json-parser still uses the
  local `Schema` + `SafeJsonParseOptions` types.
- `package.json`, `docs/api-index.md` — regenerated; the
  `./validation/validate-schema` export is gone.

Consumers migrating: change
  import { validateSchema, parseSchema } from '@socketsecurity/lib/validation/validate-schema'
to
  import { validateSchema } from '@socketsecurity/lib/schema/validate'
  import { parseSchema }    from '@socketsecurity/lib/schema/parse'

Author: jdalton

docs/api-index.md

@@ -225,8 +225,7 @@ Each entry links to the source module and shows the first sentence of its `@file
 
 ## validation/
 
-| Subpath                                                                                  | Description                                                                                           |
-| ---------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------- |
-| [`@socketsecurity/lib/validation/json-parser`](../src/validation/json-parser.ts)         | Safe JSON parsing with validation and security controls.                                              |
-| [`@socketsecurity/lib/validation/types`](../src/validation/types.ts)                     | Validation type definitions.                                                                          |
-| [`@socketsecurity/lib/validation/validate-schema`](../src/validation/validate-schema.ts) | Universal schema validation for Zod-style schemas (Zod v3, v4, and any `safeParse`-shaped duck type). |
+| Subpath                                                                          | Description                                              |
+| -------------------------------------------------------------------------------- | -------------------------------------------------------- |
+| [`@socketsecurity/lib/validation/json-parser`](../src/validation/json-parser.ts) | Safe JSON parsing with validation and security controls. |
+| [`@socketsecurity/lib/validation/types`](../src/validation/types.ts)             | Validation type definitions.                             |

package.json

@@ -675,10 +675,6 @@
       "types": "./dist/validation/types.d.ts",
       "default": "./dist/validation/types.js"
     },
-    "./validation/validate-schema": {
-      "types": "./dist/validation/validate-schema.d.ts",
-      "default": "./dist/validation/validate-schema.js"
-    },
     "./versions": {
       "types": "./dist/versions.d.ts",
       "default": "./dist/versions.js"

src/ipc.ts

@@ -9,7 +9,7 @@ import process from 'node:process'
 
 import { Type } from './external/@sinclair/typebox'
 import { getOsTmpDir } from './paths/socket'
-import { parseSchema } from './validation/validate-schema'
+import { parseSchema } from './schema/parse'
 
 /**
  * IPC stub file schema - validates the structure of stub files.