Add SD image pipeline, documentation overhaul, and fix module issues

- Add automatic SD image builds for Raspberry Pi via Forgejo Actions
- Enable binfmt emulation on cryodev-main for aarch64 cross-builds
- Add sd-image.nix module to cryodev-pi configuration
- Create comprehensive docs/ structure with installation guides
- Split installation docs into: first-install (server), reinstall, new-client (Pi)
- Add lib/utils.nix and apps/rebuild from synix
- Fix headplane module for new upstream API (tale/headplane)
- Fix various module issues (mailserver stateVersion, option conflicts)
- Add placeholder secrets.yaml files for both hosts
- Remove old INSTRUCTIONS.md (content moved to docs/)

.forgejo/workflows/build-pi-image.yml

@@ -0,0 +1,97 @@
+name: Build Raspberry Pi SD Images
+
+on:
+  push:
+    branches:
+      - main
+    paths:
+      - 'hosts/**'
+      - 'modules/**'
+      - 'templates/**'
+      - 'flake.nix'
+      - 'flake.lock'
+      - 'constants.nix'
+  workflow_dispatch:
+
+jobs:
+  build-pi-images:
+    runs-on: host
+    strategy:
+      matrix:
+        # Add new Pi hosts to this list when created
+        host: [cryodev-pi]
+      fail-fast: false
+    
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Build SD image for ${{ matrix.host }}
+        run: |
+          echo "Building SD image for: ${{ matrix.host }}"
+          echo "This may take 30-60 minutes with emulation..."
+          
+          nix build .#nixosConfigurations.${{ matrix.host }}.config.system.build.sdImage \
+            --extra-platforms aarch64-linux \
+            --out-link result-${{ matrix.host }}
+          
+          IMAGE_PATH=$(find result-${{ matrix.host }} -name "*.img.zst" -type f | head -1)
+          if [ -z "$IMAGE_PATH" ]; then
+            echo "Error: No image found!"
+            exit 1
+          fi
+          
+          cp "$IMAGE_PATH" ./${{ matrix.host }}-sd-image.img.zst
+          sha256sum ${{ matrix.host }}-sd-image.img.zst > ${{ matrix.host }}-sd-image.img.zst.sha256
+          
+          echo "Image size:"
+          ls -lh ${{ matrix.host }}-sd-image.img.zst
+
+      - name: Upload artifact
+        uses: actions/upload-artifact@v3
+        with:
+          name: ${{ matrix.host }}-sd-image
+          path: |
+            ${{ matrix.host }}-sd-image.img.zst
+            ${{ matrix.host }}-sd-image.img.zst.sha256
+
+  create-release:
+    needs: build-pi-images
+    runs-on: host
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Download all artifacts
+        uses: actions/download-artifact@v3
+        with:
+          path: artifacts/
+
+      - name: Create Release and Upload
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          VERSION="v$(date +%Y-%m-%d)-$(git rev-parse --short HEAD)"
+          
+          # Create release via API
+          curl -s -X POST \
+            -H "Authorization: token ${GITHUB_TOKEN}" \
+            -H "Content-Type: application/json" \
+            -d "{\"tag_name\": \"${VERSION}\", \"name\": \"Pi Images ${VERSION}\", \"body\": \"Raspberry Pi SD card images. See docs for usage.\", \"draft\": false, \"prerelease\": false}" \
+            "https://git.cryodev.xyz/api/v1/repos/${GITHUB_REPOSITORY}/releases" \
+            -o release.json
+          
+          RELEASE_ID=$(jq -r '.id' release.json)
+          echo "Release ID: $RELEASE_ID"
+          
+          # Upload all files
+          for file in $(find artifacts -type f); do
+            echo "Uploading: $(basename $file)"
+            curl -s -X POST \
+              -H "Authorization: token ${GITHUB_TOKEN}" \
+              -H "Content-Type: application/octet-stream" \
+              --data-binary @"$file" \
+              "https://git.cryodev.xyz/api/v1/repos/${GITHUB_REPOSITORY}/releases/${RELEASE_ID}/assets?name=$(basename $file)"
+          done
+          
+          echo "Done: https://git.cryodev.xyz/${GITHUB_REPOSITORY}/releases/tag/${VERSION}"