ci: add GitHub Actions workflows and Dependabot config

- CI workflow with test, fmt, clippy, docs, and MSRV checks
- Test on Linux, macOS, and Windows
- Test with stable and beta Rust
- Dependabot for automated dependency updates
- Funding configuration placeholder

Author: crumplecup

.github/FUNDING.yml

@@ -0,0 +1,7 @@
+# GitHub sponsors (optional)
+# github: [your-username]
+
+# Other funding options
+# patreon: your-username
+# ko_fi: your-username
+# custom: ["https://your-donation-link.com"]

.github/dependabot.yml

@@ -0,0 +1,11 @@
+version: 2
+updates:
+  - package-ecosystem: "cargo"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 10
+    reviewers:
+      - "crumplecup"
+    labels:
+      - "dependencies"

.github/workflows/ci.yml

@@ -0,0 +1,110 @@
+name: CI
+
+on:
+  push:
+    branches: [ master, main ]
+  pull_request:
+    branches: [ master, main ]
+
+env:
+  CARGO_TERM_COLOR: always
+  RUSTFLAGS: -D warnings
+
+jobs:
+  test:
+    name: Test
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+        rust: [stable, beta]
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain: ${{ matrix.rust }}
+
+      - name: Cache cargo registry
+        uses: actions/cache@v4
+        with:
+          path: ~/.cargo/registry
+          key: ${{ runner.os }}-cargo-registry-${{ hashFiles('**/Cargo.lock') }}
+
+      - name: Cache cargo index
+        uses: actions/cache@v4
+        with:
+          path: ~/.cargo/git
+          key: ${{ runner.os }}-cargo-index-${{ hashFiles('**/Cargo.lock') }}
+
+      - name: Cache cargo build
+        uses: actions/cache@v4
+        with:
+          path: target
+          key: ${{ runner.os }}-cargo-build-target-${{ hashFiles('**/Cargo.lock') }}
+
+      - name: Build
+        run: cargo build --verbose
+
+      - name: Run tests
+        run: cargo test --verbose
+
+      - name: Run tests (all features)
+        run: cargo test --all-features --verbose
+
+  fmt:
+    name: Formatting
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          components: rustfmt
+
+      - name: Check formatting
+        run: cargo fmt --all -- --check
+
+  clippy:
+    name: Clippy
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          components: clippy
+
+      - name: Run clippy
+        run: cargo clippy --all-targets --all-features -- -D warnings
+
+  docs:
+    name: Documentation
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Build documentation
+        run: cargo doc --no-deps --all-features
+        env:
+          RUSTDOCFLAGS: -D warnings
+
+  msrv:
+    name: MSRV (1.75)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust 1.75
+        uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain: "1.75"
+
+      - name: Build with MSRV
+        run: cargo build --verbose