refactor: prepare enabled state for individual operations

Currently, all states infer their enabled state by themself, e.g. by checking if maker/taker/rescan is active.
This responsibility should be moved into a context. e.g.
```json
{
"receive": {
"enabled": true,
"reasons": [],
[...]
},
"earn": {
"enabled": false,
"reasons": [{
"title": "Rescan in progress",
"description": "...",
}]
},
"send": {
"enabled": false,
"reasons": [{
"title": "Earn in progress",
"description": "...",
}]
}
[...]
}
```

(Just a concept, structure can be adapted to actual needs)

Start by tracing the states that currently infer enabled status from maker, taker, or rescan activity, then inspect the existing context structure. The work is complete when individual operations expose enabled status and reasons through a shared context, with the exact structure adapted to the project's needs.

Written by the indexing model from the issue text.