chore: add .codacy.yml config

Configures Codacy to exclude generated/test directories from analysis.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.codacy.yml

@@ -0,0 +1,17 @@
+---
+# Codacy configuration for LEDMatrix
+# Docs: https://docs.codacy.com/repositories-configure/codacy-configuration-file/
+
+engines:
+  semgrep:
+    enabled: true
+  eslint:
+    enabled: true
+
+exclude_paths:
+  # Exclude test fixtures and generated assets
+  - "plugin-repos/**"
+  - "plugins/**"
+  - "assets/**"
+  - "test/**"
+  - "scripts/debug/**"