Add build workflow and README

Author: swoboda1337

.github/workflows/build.yml

@@ -0,0 +1,80 @@
+name: Build ESP-Hosted Firmware
+
+on:
+  push:
+    branches: [main]
+    tags: ['v*']
+  pull_request:
+  workflow_dispatch:
+
+env:
+  ESP_IDF_VERSION: v5.5.1
+  ESP_HOSTED_VERSION: "2.7.0"
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        target:
+          - esp32
+          - esp32c2
+          - esp32c3
+          - esp32c5
+          - esp32c6
+          - esp32c61
+          - esp32s2
+          - esp32s3
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup ESP-IDF
+        uses: espressif/esp-idf-ci-action@v1
+        with:
+          esp_idf_version: ${{ env.ESP_IDF_VERSION }}
+          target: ${{ matrix.target }}
+
+      - name: Create project from esp_hosted slave example
+        run: |
+          idf.py create-project-from-example "espressif/esp_hosted^${{ env.ESP_HOSTED_VERSION }}:slave"
+
+      - name: Build firmware
+        working-directory: slave
+        run: |
+          idf.py set-target ${{ matrix.target }}
+          idf.py build
+
+      - name: Prepare artifacts
+        run: |
+          mkdir -p artifacts
+          cp slave/build/network_adapter.bin artifacts/network_adapter_${{ matrix.target }}.bin
+          sha256sum artifacts/network_adapter_${{ matrix.target }}.bin > artifacts/network_adapter_${{ matrix.target }}.bin.sha256
+
+      - name: Upload artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          name: firmware-${{ matrix.target }}
+          path: artifacts/
+
+  release:
+    needs: build
+    runs-on: ubuntu-latest
+    if: startsWith(github.ref, 'refs/tags/v')
+    permissions:
+      contents: write
+
+    steps:
+      - name: Download all artifacts
+        uses: actions/download-artifact@v4
+        with:
+          path: firmware
+          merge-multiple: true
+
+      - name: Create Release
+        uses: softprops/action-gh-release@v2
+        with:
+          files: firmware/*
+          generate_release_notes: true

README.md

@@ -0,0 +1,61 @@
+# ESP-Hosted Firmware
+
+Pre-built [ESP-Hosted](https://github.com/espressif/esp-hosted) co-processor firmware binaries for use with ESPHome's [ESP32 Hosted](https://esphome.io/components/update/esp32_hosted/) component.
+
+## Supported Targets
+
+| Target | Status |
+|--------|--------|
+| ESP32 | Built |
+| ESP32-C2 | Built |
+| ESP32-C3 | Built |
+| ESP32-C5 | Built |
+| ESP32-C6 | Built |
+| ESP32-C61 | Built |
+| ESP32-S2 | Built |
+| ESP32-S3 | Built |
+
+## Usage
+
+1. Download the appropriate firmware binary for your co-processor from the [Releases](https://github.com/esphome/esp-hosted-firmware/releases) page
+2. Place the `.bin` file in your ESPHome configuration directory
+3. Configure the update component in your ESPHome YAML:
+
+```yaml
+update:
+  - platform: esp32_hosted
+    firmware: coprocessor-firmware.bin
+    # SHA256 hash from the .sha256 file
+    expected_checksum: "abc123..."
+```
+
+## Building Locally
+
+To build the firmware locally:
+
+```bash
+# Clone ESP-IDF
+git clone -b v5.5.1 --recursive https://github.com/espressif/esp-idf.git
+cd esp-idf
+./install.sh esp32c6  # or your target
+source export.sh
+cd ..
+
+# Create project from ESP-Hosted example
+idf.py create-project-from-example "espressif/esp_hosted^2.7.0:slave"
+cd slave/
+
+# Build for your target
+idf.py set-target esp32c6  # or your target
+idf.py build
+
+# Output: build/network_adapter.bin
+```
+
+## Versioning
+
+Releases are tagged with the ESP-Hosted version used (e.g., `v2.7.0`).
+
+## License
+
+The ESP-Hosted firmware is licensed under the Apache License 2.0. See the [ESP-Hosted repository](https://github.com/espressif/esp-hosted) for details.