fix(doctor): ensure the doctor runs with the same settings.AppPath as Forgejo (#12901)

Attempt to address #11705 and #11028.

The docker container runs gitea by default: 1d12151086/docker/root/etc/s6/gitea/run

Whereas a user might run `forgejo doctor ...` (which is symlinked to gitea).

So the doctor expects a different value for the authorized_keys command.

This fix does the opposite of syncAppConfForGit: it fetches the `AppPath` from the database to ensure it is the same as forgejo:
1d12151086/routers/init.go (L76-L87)

### Testing

1. Make a symlink called `forgejo`, pointing to gitea `ln -s gitea forgejo`
2. Run `./gitea` and add a ssh key to a user
3. Stop `./gitea`
4. Run `./forgejo doctor check --run authorized-keys`

Without this fix, the last command should fail.
With the fix, the last command should succeed and print:
```
- [I] AppPath changed from '/home/forgejo/forgejo' to '/home/forgejo/gitea'
```

- I ran...
  - [x] `make pr-go` before pushing

### Documentation

- [ ] I created a pull request [to the documentation](https://codeberg.org/forgejo/docs) to explain to Forgejo users how to use this change.
- [x] I did not document these changes and I do not expect someone else to do it.

### Release notes

- [x] This change will be noticed by a Forgejo user or admin (feature, bug fix, performance, etc.). I suggest to include a release note for this change.
- [ ] This change is not visible to a Forgejo user or admin (refactor, dependency upgrade, etc.). I think there is no need to add a release note for this change.

*The decision if the pull request will be shown in the release notes is up to the mergers / release team.*

The content of the `release-notes/<pull request number>.md` file will serve as the basis for the release notes. If the file does not exist, the title of the pull request will be used instead.

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/12901
Reviewed-by: Mathieu Fenniak <mfenniak@noreply.codeberg.org>

services/doctor/authorizedkeys.go

@@ -13,6 +13,7 @@ import (
 	asymkey_model "forgejo.org/models/asymkey"
 	"forgejo.org/modules/log"
 	"forgejo.org/modules/setting"
+	"forgejo.org/modules/system"
 )
 
 func checkAuthorizedKeys(ctx context.Context, logger log.Logger, autofix bool) error {
@@ -20,6 +21,21 @@ func checkAuthorizedKeys(ctx context.Context, logger log.Logger, autofix bool) e
 		return nil
 	}
 
+	// make sure the doctor has the same AppPath as forgejo
+	// they can differ due to symlinks
+	// https://codeberg.org/forgejo/forgejo/pulls/12901
+	if err := system.Init(); err != nil {
+		return err
+	}
+	runtimeState := new(system.RuntimeState)
+	if err := system.AppState.Get(ctx, runtimeState); err != nil {
+		return err
+	}
+	if setting.AppPath != runtimeState.LastAppPath {
+		logger.Info("AppPath set to '%s' (was '%s')", runtimeState.LastAppPath, setting.AppPath)
+		setting.AppPath = runtimeState.LastAppPath
+	}
+
 	findings, err := asymkey_model.InspectPublicKeys(ctx)
 	if err != nil {
 		return fmt.Errorf("inspect authorized_keys failed: %w", err)