fix(editor): Fix column collapse button not visible in table view

[RicardoE105]

Summary

• Fix the column collapse ("focus") button not appearing on hover in the NDV table view
• The N8nTooltip migration from Element Plus to reka-ui (refactor(editor): Replace old N8nTooltip with new Reka UI based tooltip #22838) introduced a <span> wrapper around tooltip triggers. The broad .header span CSS rule applied overflow: hidden to this wrapper, clipping the collapse button
• Scope the CSS selector to > :first-child so only the text element gets truncation styles
• Remove negative margin-block on the collapse button that caused clipping and vertical misalignment inside the tooltip wrapper

Related ticket

https://linear.app/n8n/issue/ADO-4971

Test plan

Import this workflow, execute it, then open the Edit Fields node output in Table view:

Test workflow JSON

{
  "nodes": [
    {
      "parameters": {},
      "type": "n8n-nodes-base.manualTrigger",
      "typeVersion": 1,
      "position": [0, 0],
      "id": "94cbfb22-8799-4f3b-af5f-3c189d46123a",
      "name": "When clicking 'Execute workflow'"
    },
    {
      "parameters": {
        "mode": "raw",
        "options": {}
      },
      "type": "n8n-nodes-base.set",
      "typeVersion": 3.4,
      "position": [208, 0],
      "id": "43d672db-f2d0-443e-9a63-cf8a260fa82b",
      "name": "Edit Fields"
    }
  ],
  "connections": {
    "When clicking 'Execute workflow'": {
      "main": [
        [
          {
            "node": "Edit Fields",
            "type": "main",
            "index": 0
          }
        ]
      ]
    }
  },
  "pinData": {
    "When clicking 'Execute workflow'": [
      {
        "name": "First item",
        "code": 1,
        "data": {"some": "a", "large": "b", "json": "c", "object": "d", "with": "e", "many": "f", "keys": "g"}
      },
      {
        "name": "Second item",
        "code": 2,
        "data": {"some": "n", "large": "m", "json": "o", "object": "p", "with": "q", "many": "r", "keys": "s"}
      },
      {
        "name": "Third item",
        "code": 3,
        "data": {"some": "x", "large": "y", "json": "z", "object": "w", "with": "v", "many": "u", "keys": "t"}
      },
      {
        "name": "Third item",
        "code": 3,
        "data": {"some": "x", "large": "y", "json": "z", "object": "w", "with": "v", "many": "u", "keys": "t"}
      },
      {
        "name": "Third item",
        "code": 3,
        "data": {"some": "x", "large": "y", "json": "z", "object": "w", "with": "v", "many": "u", "keys": "t"}
      },
      {
        "name": "Third item",
        "code": 3,
        "data": {"some": "x", "large": "y", "json": "z", "object": "w", "with": "v", "many": "u", "keys": "t"}
      },
      {
        "name": "Third item",
        "code": 3,
        "data": {"some": "x", "large": "y", "json": "z", "object": "w", "with": "v", "many": "u", "keys": "t"}
      }
    ]
  }
}

• Hover over any column header — the collapse (chevrons) button should appear
• Click the button — other columns should collapse to single-line truncated text
• Click the reset button (next to search icon) to uncollapse
• Verify button appears on hover for all column types (simple values and JSON objects)
• Verify button is vertically centered in the header row

[github-actions]

⚠️ Ownership acknowledgement required

Please add or check the following item in your PR description before this can be merged:

- [x] I have seen this code, I have run this code, and I take responsibility for this code.

[codecov]

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[cubic-dev-ai]

No issues found across 1 file

[RicardoE105]

fIxes #26393