feat(ci): add codecov.yml to exclude 3rdparty from coverage

Add codecov configuration file to exclude directories from coverage report:
- Exclude 3rdparty/** directory (third-party libraries)
- Exclude test/** directory (test code)
- Exclude demo/** directory (demo applications)

This ensures only project source code is included in coverage metrics.

Author: mutouyun

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