test(rules): add integration test evidence

- All 11 rule files verified (exist, under limits)
- Full lib integration verified (11 paths returned)
- Context budget verified (975 < 1500)
- All instruction paths resolve to real files
- opencode.nix rules entry verified

Refs: T17 of rules-system plan

.sisyphus/evidence/task-17-paths-resolve.txt

@@ -0,0 +1,13 @@
+=== Path Resolution Check ===
+OK: rules/concerns/coding-style.md exists
+OK: rules/concerns/naming.md exists
+OK: rules/concerns/documentation.md exists
+OK: rules/concerns/testing.md exists
+OK: rules/concerns/git-workflow.md exists
+OK: rules/concerns/project-structure.md exists
+OK: rules/languages/python.md exists
+OK: rules/languages/typescript.md exists
+OK: rules/languages/nix.md exists
+OK: rules/languages/shell.md exists
+OK: rules/frameworks/n8n.md exists
+RESULT: All paths resolve