feat(ci): exclude 3rdparty folder from codecov coverage

- Add codecov.yml configuration to exclude 3rdparty, test, and demo directories
- Update GitHub Actions workflow with exclude parameter in codecov-action
- Ensures only project source code is included in coverage metrics

This provides double protection:
1. codecov.yml filters on CodeCov service side
2. workflow exclude filters during upload

.github/workflows/codecov.yml

@@ -30,5 +30,9 @@ jobs:
       uses: codecov/codecov-action@v4.0.1
       with:
         verbose: true
+        exclude: |
+          3rdparty/**
+          test/**
+          demo/**
       env:
         CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}

codecov.yml

@@ -0,0 +1,30 @@
+codecov:
+  require_ci_to_pass: yes
+
+coverage:
+  precision: 2
+  round: down
+  range: "70...100"
+
+  status:
+    project:
+      default:
+        target: auto
+        threshold: 0%
+        base: auto
+    patch:
+      default:
+        target: auto
+        threshold: 0%
+        base: auto
+
+ignore:
+  - "3rdparty/**/*"
+  - "3rdparty/**"
+  - "test/**/*"
+  - "demo/**/*"
+
+comment:
+  layout: "reach,diff,flags,tree"
+  behavior: default
+  require_changes: false