fix(canvas-table): unmount cell-editor React root on end

[Aias00]

Related issue

Closes #2070

Summary

In InputIEditor, createElement called ReactDOM.createRoot(inputContainer).render(...) inline and discarded the root reference. onEnd only detached the DOM node (removeChild) — the React fiber tree, state, effects, and handlers inside the rendered component were never torn down, leaking on every cell-edit open/close cycle. Now the root is stored on the instance (this.root) and unmount()ed in onEnd (and this.root nulled). Applied at both createElement sites: the base InputEditor and DateEditor.createElement (the date editor inherits the base onEnd, and createElement is only invoked when inputContainer is null, so there is no double-create that would orphan a prior root).

Affected surfaces

• Frontend / Web
• Backend / API / Storage
• Database plugin / Driver
• JCEF / Desktop packaging
• CI / Build / Release
• Documentation only

Verification

• Commands and results:
  • npx tsc --noEmit -p chat2db-community-client/tsconfig.json — no errors for InputIEditor/index.tsx.
  • npx eslint src/blocks/CanvasTable/editor/InputIEditor/index.tsx — no errors.
• Manual verification: On onEnd, this.root?.unmount() is now called (tearing down the React tree), and this.root is nulled. createElement is guarded by if (!this.inputContainer) so it is not called twice without an intervening onEnd.
• UI evidence: N/A

Risk and compatibility

• Public API or stored data: N/A.
• Database or driver compatibility: N/A.
• Network, privacy, or security: N/A.
• Community / Local / Pro boundary: N/A.
• Backward compatibility: Only adds cleanup on onEnd; edit/create behavior unchanged.

Reviewer map

• Start here: blocks/CanvasTable/editor/InputIEditor/index.tsx — new root field on InputEditor; both createElement sites store this.root = ReactDOM.createRoot(...) then this.root.render(...); onEnd calls this.root?.unmount() and nulls it.
• Failure condition: React roots still leak across cell-edit open/close.
• Rollback or disable path: Revert this single commit.

Contributor declaration

• I linked the Issue that defines this change.
• I tested the affected behavior and reported the actual results above.
• I did not include credentials, private data, or generated build output.
• I disclosed substantial AI assistance below, or this PR contains no substantial AI-generated code.

AI assistance: The fix, verification, and PR description were produced with Claude Code assistance.

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[openai0229]

Reviewed the React root ownership and unmount lifecycle across the canvas table editors. No blocking findings; LGTM.