[lexical] Bug Fix: EditorState.clone() keeps the _parsed flag

[LeSingh1]

Description

EditorState._parsed is documented as "True if this EditorState was parsed
without running transforms". parseEditorState sets it, and setEditorState
is its only consumer — when the state it is handed has _parsed, it dirty-marks
every node so registered node transforms (and the hydrate-time shadow-root
normalization) run against the freshly parsed content. That is the fix from
#7876.

EditorState.clone() carried _nodeMap, the selection and _slotsUsed, but
not _parsed, so the clone always reported false. setEditorState reads the
flag off its argument, which means the documented "apply a state without
focusing the editor" form silently lost the behaviour:

// packages/lexical-website/docs/concepts/editor-state.md
// Passing `null` as a selection value to prevent focusing the editor
editor.setEditorState(editorState.clone(null));

setEditorState(parsed) ran the transforms; setEditorState(parsed.clone(null))
did not — the same content, applied two documented ways, with different results.

A clone describes the same content as the state it came from, so it is still
"parsed without running transforms" if the original was. Carry the flag.

This does not make transforms re-run later: cloneEditorState — the copy
setEditorState and every commit make internally — still starts a fresh state
with _parsed === false, which is where the flag is consumed. clone() has no
callers inside packages/lexical; it is a public API.

Test plan

New case in packages/lexical/src/__tests__/unit/Issue7876Repro.test.ts,
alongside the existing direct-setEditorState case it mirrors.

Before

$ npx vitest run packages/lexical/src/__tests__/unit/Issue7876Repro.test.ts

 FAIL  |unit| .../Issue7876Repro.test.ts > Issue #7876: setEditorState triggers transforms on parsed state > text-node transform fires for a cloned parsed state (the documented no-focus form)
AssertionError: expected false to be true // Object.is equality

- Expected
+ Received

- true
+ false

 Test Files  1 failed (1)
      Tests  1 failed | 4 passed (5)

After

$ npx vitest run packages/lexical/src

 Test Files  65 passed (65)
      Tests  1348 passed | 1 skipped (1349)

$ npx vitest run packages/lexical-history packages/lexical-yjs packages/lexical-react

 Test Files  38 passed (38)
      Tests  285 passed (285)

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