chore: Symlink CLAUDE.md to AGENTS.md (#2279)

Creates a CLAUDE.md symlink pointing to AGENTS.md so Claude Code (the
Anthropic CLI tool) automatically picks up the project's AI assistant
rules without duplicating content.

https://claude.ai/code/session_01Y6n2rcJX5NJ3UqiCJ45WZ9

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Low Risk**
> Adds a new top-level rules file reference only; no product code or
runtime behavior is affected.
> 
> **Overview**
> Adds `CLAUDE.md` containing `AGENTS.md` so Claude Code can
automatically pick up the repository’s AI assistant rules without
duplicating the vendor-agnostic guidelines.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
f5a910d. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

---------

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Michał Olender <92638966+TC-MO@users.noreply.github.com>

Author: 3 people

.markdownlintignore

@@ -2,3 +2,4 @@ node_modules
 build
 .claude
 AGENTS.md
+CLAUDE.md

CLAUDE.md

@@ -0,0 +1 @@
+AGENTS.md