Align superscript/subscript rendering in legacy block editor edit view

[Copilot]

• Locate and read the bubble menu component (html + ts + spec)
• Add toggleSuperscript() and toggleSubscript() methods to dot-bubble-menu.component.ts that unset the opposite mark before toggling
• Update dot-bubble-menu.component.html to call the new methods
• Add unit tests to dot-bubble-menu.component.spec.ts verifying both methods enforce mutual exclusion
• All two new tests pass
• Build verified clean
• Run parallel validation (Code Review + CodeQL)

[claude]

Claude finished @fmontes's task in 1m 56s —— View job

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PR Review

• Read changed files
• Analyze code for issues
• Post review findings

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Incomplete mutual-exclusion fix — slash command path is not covered

actions-menu.extension.ts uses setSuperscript() / setSubscript() directly (no mutual exclusion):

// core-web/libs/block-editor/src/lib/extensions/action-button/actions-menu.extension.ts
subscript: () => editor.chain().setSubscript().focus().run(),
superscript: () => editor.chain().setSuperscript().focus().run(),

A user who applies subscript via the bubble menu and then adds superscript via the /superscript slash command will end up with both marks active simultaneously — the exact bug this PR claims to fix. The bubble menu and slash command menu are two paths to the same marks; only one of them enforces exclusion now. Fix this →

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CSS is correct but worth documenting why

vertical-align: super/sub are browser defaults; they have to be explicitly set here because ProseMirror's base stylesheet (prosemirror.css) resets sup/sub to baseline. The fix is right, but a comment explaining that would prevent a future reader from deleting them as "redundant."

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Test calls protected method via bracket access

component['toggleSuperscript']();

Works at runtime, but if the method is renamed TypeScript won't catch the stale test reference. A small risk in a file that is otherwise well-structured.

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Everything else — the chain ordering, the mock design, the afterEach cleanup, the CSS placement — is clean.