Quick Settings, substitutions but with a GUI

**Describe the problem you have/What new integration you would like**

Quick settings would be a way of changing some things in the config without opening it. They could be defined in the config file and then be shown in the ESPHome Dashboard. I have made a small example mockup for how it could look like:

Config Section:

```yaml
settings:
- name:
description: "Name"
default: "Air Quality Sensor"
type: String
- sensor-prefix:
description: "Sensor Prefix"
default: ""
type: String
- voc-limit:
description: "VOC Limit"
default: 300
type: Integer
max: 1000
min: 0
```
These settings could then be used in the rest of config, just like the substitutions.
And in the Dashboard it could look something like this:



**Please describe your use case for this integration and alternatives you've tried:**

It would be easy for inexperienced users to change for example the name or a prefix of the device. This would be specially useful when you make devices and share or sell them cause the user wouldn't need to fiddle with a yaml config and could use a nice GUI to change curated settings by the creator.

**Additional context**

Start by reviewing how ESPHome configuration substitutions are defined and consumed, then inspect the ESPHome Dashboard area responsible for editing configuration. Clarify the settings schema, supported types and constraints, persistence, and how values reach generated device configuration. Done means a documented design and an implemented, tested GUI workflow for defining and changing these settings.

Written by the indexing model from the issue text.