Add Pantograph to awesome-structure-editors list

[Copilot]

Adds Pantograph to the structural code editor projects section as requested in issue #793346a2.

About Pantograph:
Pantograph is a fluid and typed structure editor developed by Jacob Prinz and Henry Blanchette, with an associated POPL 2025 paper. It introduces novel concepts like "zipper editing" with tree selections and typed refactoring operations that automatically maintain program well-typedness during structural edits.

Entry details:

• Position: Placed between Envision (99⭐) and Freon (70⭐) based on star count (93⭐)
• Properties: 🎓 Academic, ⌨️ Text editing UX, 👶 New language, λ Functional, 🌐 Works in browser
• Language: PureScript
• Description: "A fluid and typed structure editor"
• Updated: 2025

The entry follows the existing format and maintains proper alphabetical ordering within star count groups. You can try Pantograph online at https://pantographeditor.github.io/Pantograph/.

Fixes #793346a2

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• https://api.github.com/repos/yairchu/awesome-structure-editors
  • Triggering command: awesome-lint (http block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

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This section details on the original issue you should resolve

<issue_title>Add Pantograph</issue_title>
<issue_description>See https://github.com/jeprinz/pantograph</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes #42

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