[FIX] "Start Contributing" button redirects to 404 — patch included

Problem

Issue #852: The "Start Contributing" button on the roadmap page (https://opencut.app/roadmap) links to https://github.com/OpenCut-app/OpenCut/blob/main/.github/CONTRIBUTING.md, which returns a 404 Not Found because no CONTRIBUTING.md exists at that path.

Fix

Created .github/CONTRIBUTING.md at the path the button already points to. The file explains that the project is still in early architecture design and directs contributors to the Discord and issues page instead.

Patch

The fix is available on my fork:

Branch: fix/contributing-url
PR: https://github.com/zerafachris/OpenCut/compare/fix/contributing-url?expand=1

diff --git a/.github/CONTRIBUTING.md b/.github/CONTRIBUTING.md
new file mode 100644
index 0000000..957df07
--- /dev/null
+++ b/.github/CONTRIBUTING.md
@@ -0,0 +1,5 @@
+# Contributing to OpenCut
+
+We're not set up to take outside contributions yet while the architecture is being designed. If you want to follow along, ask questions, or just hang out, [join the Discord](https://discord.gg/zmR9N35cjK) or [open an issue](https://github.com/opencut-app/opencut/issues).
+
+Looking for the classic version? See [opencut-app/opencut-classic](https://github.com/OpenCut-app/opencut-classic).

Review the roadmap page link and the proposed .github/CONTRIBUTING.md file. Confirm that the button resolves to the new file and that its Discord, issues, and classic-version links match the intended guidance. The proposed fix is already available on the contributor's fork branch fix/contributing-url.