feat: implement error handling and validation middleware, enhance result handling

Co-authored-by: Copilot <copilot@github.com>

apps/backend/src/lib/http/validate.ts

@@ -0,0 +1,52 @@
+
+import { zValidator } from '@hono/zod-validator'
+import type { ZodSchema } from 'zod'
+import { validationProblem } from './problem-builders'
+import { zodIssuesToRecord } from './zod-issues'
+
+type ValidationTarget = 'json' | 'query' | 'param' | 'header' | 'form'
+
+function makeValidator<TSchema extends ZodSchema>(
+  target: ValidationTarget,
+  schema: TSchema
+) {
+  return zValidator(target, schema, (result, c) => {
+    if (result.success) {
+      return
+    }
+
+    const requestId = c.get('requestId') as string | undefined
+    const instance = requestId ? `/requests/${requestId}` : undefined
+
+    return c.json(
+      validationProblem({
+        detail: `Invalid ${target} data`,
+        instance,
+        errors: zodIssuesToRecord(result.error.issues)
+      }),
+      400
+    )
+  })
+}
+
+export const validate = {
+  json<TSchema extends ZodSchema>(schema: TSchema) {
+    return makeValidator('json', schema)
+  },
+
+  query<TSchema extends ZodSchema>(schema: TSchema) {
+    return makeValidator('query', schema)
+  },
+
+  param<TSchema extends ZodSchema>(schema: TSchema) {
+    return makeValidator('param', schema)
+  },
+
+  header<TSchema extends ZodSchema>(schema: TSchema) {
+    return makeValidator('header', schema)
+  },
+
+  form<TSchema extends ZodSchema>(schema: TSchema) {
+    return makeValidator('form', schema)
+  }
+}