Remove catppuccin-gtk overlay workaround — nixpkgs pin now includes the upstream fixes

[patflynn]

The pinned nixpkgs rev (18b9261cb3294b6d2a06d03f96872827b8fe2698) now contains both upstream fixes that PR #618 was mirroring locally:

• 455d916d0c — python3Packages.catppuccin: fix build with matplotlib 3.11+ (Fix #129 (caused by matplotlib 3.11 deprecating mpl.style.core) catppuccin/python#130)
• 894acc94f6 — catppuccin-gtk: fix build with python314+

Both commits verified as ancestors of the pinned revision. The local mirror added in #618 (the nixpkgs.overlays block in modules/common/desktop.nix plus the two verbatim patch files) is now redundant, so this PR removes it:

• Deletes the temporary nixpkgs.overlays block from modules/common/desktop.nix
• Deletes modules/common/patches/catppuccin-gtk-python-3.14.patch and modules/common/patches/catppuccin-python-matplotlib-3.11.patch
• Removes the now-empty modules/common/patches/ directory

References: catppuccin/python#129 and catppuccin/python#130 (upstream issue/fix).

Verification

This cloud session cannot run nix, so cosmo's CI (the build-nixos dry-run eval) is the verification gate for this PR. A full local build of the affected hosts should be confirmed via the machine's converge loop after merge.

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Once this merges, the routine that opened this PR can be deleted at https://claude.ai/code/routines.

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Generated by Claude Code

[gemini-code-assist]

Code Review

This pull request removes the temporary nixpkgs overlay and associated patch files for catppuccin-gtk and catppuccin in modules/common/desktop.nix, as the upstream nixpkgs channel has now integrated these fixes. I have no feedback to provide.

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