Register <label> in defaultProcessorMap to prevent spurious div injection on paste

[Copilot]

Pasting HTML containing <label> elements caused an extra <div> to be injected inside each label, resulting in double-line rendering. The root cause: label was absent from defaultProcessorMap, so it fell through to generalProcessor ('*'), which wraps unknown elements in a ContentModelGeneralBlock — serialized back as a <div>.

Changes

• defaultProcessors.ts — Register label: knownElementProcessor in defaultProcessorMap. This treats <label> like other inline-capable elements (span, b, em, etc.), processing its children as segments rather than wrapping them in a new block.

• knownElementProcessorTest.ts — Add a test case verifying that a <label> with text content produces a paragraph with a text segment and no extra block wrappers.

Before the fix, pasting a <label>Test</label> would produce:

<label><div>Test</div></label>

After the fix, the label content is preserved as-is without any injected wrapper.

• Fixes Pasting labels sometimes adds a Div element that is not present in the source of the copy #2447

[github-actions]

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[JiuqingSong]

@copilot The PR has test case failure. Fix it.

[Copilot]

@copilot The PR has test case failure. Fix it.

Fixed in commit Fix test: label is inline, expect one implicit paragraph not two blocks. The test was wrong: <label> has display: inline by default, so knownElementProcessor treats it as an inline element — its text content is appended to the current (implicit) paragraph rather than creating a new block paragraph followed by an empty trailing one. The expected value in the test now matches that actual inline behavior.