chore: cleanup repository and add Gitea Actions build workflow

- Update .gitignore to exclude build artifacts and IDE files
- Remove tracked .idea and .vscode directories from index
- Add .gitea/workflows/build.yaml for CI
- Commit existing source changes and README updates

.gitea/workflows/build.yaml

@@ -0,0 +1,13 @@
+name: Build
+on: [push]
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install dependencies
+        run: sudo apt-get update && sudo apt-get install -y cmake build-essential
+      - name: Configure CMake
+        run: cmake -B build
+      - name: Build
+        run: cmake --build build