Print full level names in console output instead of three-letter abbreviations

### Problem
Console output labels every line with a three-letter level abbreviation ([src/Fallout.Build/Logging.cs:27-28](https://github.com/Fallout-build/Fallout/blob/main/src/Fallout.Build/Logging.cs#L27-L28)):

```
22:49:44 [DBG] git version 2.50.1 (Apple Git-155)
22:49:44 [INF] > /usr/bin/git --version
22:49:44 [WRN] a warning line
22:49:44 [ERR] an error line
```

`VRB`, `DBG`, `INF`, `WRN`, `ERR` and `FTL` are not self-explaining. A reader has to learn the codes, and `VRB` versus `DBG` is not obvious even once you have.

The abbreviations exist to keep the level column a fixed width so messages line up. That is worth having, but it is not worth paying for with abbreviations — alignment should come from the layout, not from truncating the words.

### Outcome
Console lines are labelled with the full level name.

```
22:49:44 [Debug] git version 2.50.1 (Apple Git-155)
22:49:44 [Information] > /usr/bin/git --version
22:49:44 [Warning] a warning line
22:49:44 [Error] an error line
```

### Acceptance criteria
- [ ] Console output shows `[Debug]`, `[Information]`, `[Warning]`, `[Error]`, `[Verbose]`, `[Fatal]`
- [ ] The errors-and-warnings summary block uses the same names
- [ ] Level colouring is unaffected
- [ ] Specs cover every level for both console templates

### Notes
Message alignment is deliberately not preserved here. Column layout is #391s job, where Spectre owns the frame and can indent or lay out a real column instead. Scope is the console templates only: the `build.log` file templates keep their compact single-letter column format.

Start at src/Fallout.Build/Logging.cs:27-28 and locate the console templates plus the errors-and-warnings summary. Run the existing logging specs to identify both console-template cases. Done means every level uses its full name in both outputs, level colouring remains unchanged, and specs cover Verbose, Debug, Information, Warning, Error, and Fatal.

Written by the indexing model from the issue text.