GeezerVison

…413)

Stacked on #412.

## Description
When nothing is known about the receiver's state (e.g. a parameter with
no state refinement), the error used to say only that no state
information is known. For classes with a state machine, it now lists the
constructors and the calls that lead to a state allowing the failing
call, each with the states it is called from.

Classes without a state machine keep the previous general hint.

## Example
```java
static void use(File f) {
    f.read(); // read() needs open
}
```
```
 --> The state of f is unknown here. To get it to open, use: f.open() (from created)
```

## Type of change
- [x] New feature

## Checklist
- [x] Added tests: `ErrorStateHintUnknownState`. `TestStateHints` also
checks that a class without `@StateSet` keeps the general hint.
- [x] `mvn test` passes locally

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 5.5 <[email protected]>

## Description
#412, #413 and #414 were merged into their stacked base branches instead
of `main`: once #411 was merged, their bases were never retargeted.
Their code is only on `feat/state-hints-unknown`.

This PR applies the three reviewed commits on top of `main`, unchanged:
- Explain dead ends in failing state transitions (#412)
- List the calls that reach an allowed state when the state is unknown
(#413)
- Build each class's state machine once per checker (#414)

The hint and state machine files are identical to
`feat/state-hints-unknown`. Rebase-merging keeps the three commits
separate.

## Checklist
- [x] `mvn test` passes locally on top of the current `main` (#408,
#409)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 5.5 <[email protected]>