feat: introduced omptype validation package and migrated workspace dependencies

- Introduce `@oh-my-pi/omptype` as a new ArkType-compatible schema validation package featuring a lazy JIT runtime, JSON Schema emission, and compatibility adapters.
- Replace `arktype` across workspace packages and test utilities with `@oh-my-pi/omptype`.
- Add benchmark suites, tests, and documentation for the new validation engine and adapters.
- Update workspace build, test runner, and release configurations to include the new package.

packages/coding-agent/test/task/task-schema.test.ts

@@ -1,9 +1,9 @@
 import { afterEach, describe, expect, it, vi } from "bun:test";
+import { type } from "@oh-my-pi/omptype";
 import { Settings } from "@oh-my-pi/pi-coding-agent/config/settings";
 import { TaskTool, taskSchema } from "@oh-my-pi/pi-coding-agent/task";
 import * as discoveryModule from "@oh-my-pi/pi-coding-agent/task/discovery";
 import type { ToolSession } from "@oh-my-pi/pi-coding-agent/tools";
-import { type } from "arktype";
 
 // Contract: the single-spawn schema (`task.batch: false`; the exported
 // `taskSchema` instance) carries no batch fields while accepting a caller

packages/coding-agent/test/task/wire-schema.test.ts

@@ -1,10 +1,10 @@
 import { afterEach, describe, expect, it, vi } from "bun:test";
+import { type } from "@oh-my-pi/omptype";
 import { Settings } from "@oh-my-pi/pi-coding-agent/config/settings";
 import { TaskTool, taskSchema } from "@oh-my-pi/pi-coding-agent/task";
 import * as discoveryModule from "@oh-my-pi/pi-coding-agent/task/discovery";
 import { getTaskSchema, oneLineLabel } from "@oh-my-pi/pi-coding-agent/task/types";
 import type { ToolSession } from "@oh-my-pi/pi-coding-agent/tools";
-import { type } from "arktype";
 
 // Contract: the task tool's wire shape is flat `{ name?, agent?, task, isolated? }`
 // (batch: `{ context, tasks[] }` of the same items). `agent` defaults to the