refactor: migrate monorepo from pnpm to Bun runtime and workspaces

- root: bun workspaces via package.json, packageManager bun@1.4.0, scripts use bun --filter
- backend: Bun.serve, bun test (vitest removed), bun --watch dev script, tsconfig types bun
- tests: migrate 6 test files from vitest to bun:test (mock.module)
- validate: replace @hono/zod-validator with hono validator + zod safeParse (fixes TS2589)
- lockfile: bunfig.toml saveTextLockfile, regenerated bun.lock (text) for turbo
- docs: AGENTS.md, README.md, stack.md updated to Bun stack

apps/backend/src/http/validate.ts

@@ -1,57 +1,62 @@
-import { zValidator } from '@hono/zod-validator';
-import type { Context } from 'hono';
-import type { ZodIssue, ZodSchema } from 'zod';
+import type { Context, MiddlewareHandler } from 'hono';
+import { validator } from 'hono/validator';
+import type { ZodTypeAny, z } from 'zod';
 import { validationProblem } from './problem-builders';
 import { zodIssuesToRecord } from './zod-issues';
 
 type ValidationTarget = 'json' | 'query' | 'param' | 'header' | 'form';
 
-function makeValidator(target: ValidationTarget, schema: ZodSchema) {
-  return zValidator(
-    target,
-    schema,
-    (result: { success: boolean; error?: { issues: ZodIssue[] } }, c: Context) => {
-      if (result.success) {
-        return;
-      }
+type ValidationInput<S extends ZodTypeAny, T extends ValidationTarget> = {
+  out: { [K in T]: z.output<S> };
+};
 
-      const requestId = c.get('requestId');
-      const instance = requestId ? `/requests/${requestId}` : undefined;
-      const issues = result.error?.issues ?? [];
+function makeValidator<S extends ZodTypeAny, T extends ValidationTarget>(
+  target: T,
+  schema: S,
+): MiddlewareHandler<{}, string, ValidationInput<S, T>> {
+  const middleware = validator(target, (value: unknown, c: Context) => {
+    const result = schema.safeParse(value);
 
-      return c.json(
-        validationProblem({
-          detail: `Invalid ${target} data`,
-          instance,
-          errors: zodIssuesToRecord(issues),
-        }),
-        400,
-        {
-          'Content-Type': 'application/problem+json',
-        },
-      );
-    },
-  );
+    if (result.success) {
+      return result.data;
+    }
+
+    const requestId = c.get('requestId');
+    const instance = requestId ? `/requests/${requestId}` : undefined;
+
+    return c.json(
+      validationProblem({
+        detail: `Invalid ${target} data`,
+        instance,
+        errors: zodIssuesToRecord(result.error.issues),
+      }),
+      400,
+      {
+        'Content-Type': 'application/problem+json',
+      },
+    );
+  });
+
+  return middleware as unknown as MiddlewareHandler<{}, string, ValidationInput<S, T>>;
 }
-
 export const validate = {
-  json(schema: ZodSchema) {
+  json<S extends ZodTypeAny>(schema: S) {
     return makeValidator('json', schema);
   },
 
-  query(schema: ZodSchema) {
+  query<S extends ZodTypeAny>(schema: S) {
     return makeValidator('query', schema);
   },
 
-  param(schema: ZodSchema) {
+  param<S extends ZodTypeAny>(schema: S) {
     return makeValidator('param', schema);
   },
 
-  header(schema: ZodSchema) {
+  header<S extends ZodTypeAny>(schema: S) {
     return makeValidator('header', schema);
   },
 
-  form(schema: ZodSchema) {
+  form<S extends ZodTypeAny>(schema: S) {
     return makeValidator('form', schema);
   },
-};
+};