fix: update ITables to 2.4+

[Pybsama]

Issue #, if available:

Fixes #780

Description of changes:

• update the ITables dependency range to >=2.4.0,<3.0.0 in both dependency declarations so raw table content uses the newer default HTML escaping
• preserve the existing single-encoded display for SPARQL, Gremlin, and openCypher query results without enabling HTML globally
• encode untrusted query-result column labels on a display-only copy before opting those pre-encoded cells into allow_html=True
• add regression coverage for raw HTML escaping, double escaping, unsafe headers, source-frame immutability, and RangeIndex preservation

Local validation:

• 582 unit tests with ITables 2.4.0
• 582 unit tests with ITables 2.9.1
• repository CI-equivalent Flake8 checks
• sdist and wheel build, isolated wheel installation, and pip check

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[Pybsama]

Fresh current-main validation is complete.

• The public head remains 400560461166dd5ed6d02c6c21be425adbe73074; it is ahead 2 / behind 3 relative to current main 83f55e33a79206ac19155507188d1708245a551a, and the conflict-free merge tree is d21f286d17b75a0a9043a669b2f6f7a3f14862f2.
• On that exact merge tree, Python 3.9.6 + ITables 2.9.1 and Python 3.9.6 + the minimum ITables 2.4.0 each pass all 594 unit tests. The four focused cell/header escaping contracts pass on both versions, and pip check is clean in both environments.
• Both repository Flake8 commands pass. A real 5.3.0 sdist and wheel build completed, including the production widget/JupyterLab build; the wheel metadata contains itables<3.0.0,>=2.4.0 and Python <3.14,>=3.9.
• A clean wheel-only environment installed 140 packages, passed pip check, loaded graph_notebook from site-packages, and passed the four security/compatibility contracts against the installed artifact.
• The existing public Unit Tests checks for Python 3.9, 3.10, 3.11, 3.12, and 3.13 are all successful. The current-main production build still reports the repository's existing npm audit and bundle-size warnings; this PR does not change frontend dependencies or apply an unrelated audit fix.

Issue #780 remains open with no competing implementation, and current main still constrains ITables to 2.0–2.1. I am marking this PR ready for review without rewriting the two existing GitHub Verified commits.