I think it's a legacy that it used to be static.
It could be simplified now.

I'd like to reuse it for #2777 

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

## Summary by CodeRabbit

* **Refactor**
* Improved internal logic for endpoint factory creation to enhance
maintainability. No changes to user-facing features or behavior.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

### Dedication


![image](https://github.com/user-attachments/assets/47dc18f9-70fa-4276-9c79-2a84ef360642)

**Sara Millerey González** was a 32 years young trans woman from Bello,
Antioquia, Colombia.
She was killed in April 2025. Millerey was raped, tortured, and thrown
into a ravine by a group of men. Denounced as a hate crime by press and
Antioquia's mayor, the Colombian National Working Group on Violence
Based on Victims' Sexual Orientation or Gender Identity is collaborating
with the Attorney's General's Office on identifying remaining suspects.

Transgender women suffer too frequently from transphobic violence and
cruelty, being the less protected social group. I'd like to raise an
awareness of this problem. Humans should be creators — not killers. But
most importantly, I want every transgender girl to have an opportunity
to create applications quickly and, in general, learn to write code
easily in order to receive job offers and leave dangerously transphobic
territories for more favorable and civilized ones, and live happily
there. Protect transgender women.

### Breaking

- `zod` version is `^4.0.0`;
  - Compatibility with `zod@^3` is dropped;
  - You SHOULD now `import { z } from "zod"` without the `/v4` suffix;
- Node.js version is `^20.19.0 || ^22.12.0 || ^24.0.0`;
  - The framework distribution is now ESM-only (finally);
  - All the Node.js versions listed above support `require(ESM)` syntax;
- Changes to the `Middleware` class:
- When the `input` schema is not defined, the `input` argument of the
`handler` method is now `unknown`;
- Plugin changes to metadata:
  - `example` removed;
  - object-based `examples` removed (only array remains);
- use either `.example()` or `.meta({})` with `examples` being an array.
- Public `getExamples()` helper removed:
  - use `.meta()?.examples` or `globalRegistry.get()?.examples` instead.

### Content

- #2622 
- #2711 
- #2740 
- #2742 
- #2777 
- #2809 
- #2814 
- #2815 
- #2842 
- #2843 
- #2844 

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

## Summary by CodeRabbit

* **New Features**
* Dropped support for Zod v3; now requires Zod v4 and updates all
imports to use `"zod"` directly.
* Framework is now distributed as ESM-only and supports Node.js
^20.19.0, ^22.12.0, or ^24.0.0.
  * Introduced a unified empty schema utility for input/output defaults.
* Added Vitest configuration with experimental eventsource flag for
testing.

* **Breaking Changes**
* Removed the public `getExamples()` helper; access examples via
`.meta()?.examples` or the global registry.
* Middleware and factory input schemas now default to `undefined` when
omitted, not an empty object schema.
* Dropped support for object-based `examples` in schema metadata; use
`.example()` or array-based `examples` instead.
* Removed deprecated enum and literal depicters from documentation
helpers.
* Updated import paths from `"zod/v4"` to `"zod"` throughout codebase
and examples.
* Adjusted migration rules to reflect import and metadata changes only.

* **Bug Fixes**
* Improved handling of empty schemas and type inference for middleware
and endpoint factories.

* **Chores**
* Updated documentation and changelogs for new Zod import paths and
version requirements.
* Updated build, test, and lint configurations for ESM-only output and
new dependency versions.
* Adjusted GitHub workflows to monitor new branches and updated Node.js
versions.
* Removed legacy migration rules and simplified migration logic focusing
on import and metadata changes.
* Removed legacy dependencies like `undici` and adjusted package
metadata.
  * Simplified ESLint and tsup configurations for ESM-only builds.
  * Updated startup logo dedication message.

* **Tests**
* Refactored and updated tests to align with new schema defaults and Zod
v4 usage.
* Simplified migration tests and rules to focus on import path changes.
  * Added tests for new empty schema utilities.

* **Style**
  * Updated dedication message in the startup logo.

* **Revert**
* Removed legacy and deprecated migration logic and configuration
overrides.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>