Stop blanking out the main browser (BL-16047)

[andrew-polk]

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This change is 

[andrew-polk]

src/BloomExe/web/controllers/AppApi.cs line 244 at r1 (raw file):

                return;
            }

The changes in this file are directly related to the fix, but they are things which the AI found which should have been in place while we were analyzing the real problem.

[andrew-polk]

src/BloomExe/Edit/EditingView.cs line 1605 at r1 (raw file):

            _mainBrowser?.RunJavascriptFireAndForget(
                "workspaceBundle.switchContentPage('about:blank');"
            );

The original code here just blanked out the edit view's browser. It was mistakenly applied to the whole main browser during the single-browser conversion.

[cubic-dev-ai]

No issues found across 2 files

[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

View in Devin Review to see 3 additional findings.