Add Woodpecker CI pipeline with semantic versioning

Pipeline stages:
- restore: Restore NuGet dependencies
- build: Build in Release mode
- test: Run test suite
- version: Determine version from git tags
- package-nuget: Create NuGet package (main branch)
- package-docker: Build multi-arch Docker image (tags only)
- release: Create GitHub release with artifacts (tags only)

Versioning:
- Tags (v1.0.0) → version 1.0.0
- Main branch → version X.Y.Z-dev.main.abc1234
- PRs → version X.Y.Z-dev.branch.abc1234

Docker image published to ghcr.io/barryw/paperlessmcp

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

PaperlessMCP/Dockerfile

@@ -1,5 +1,6 @@
 # Build stage
 FROM mcr.microsoft.com/dotnet/sdk:10.0-preview AS build
+ARG VERSION=0.0.0-dev
 WORKDIR /src
 
 # Copy project file and restore dependencies
@@ -8,12 +9,20 @@ RUN dotnet restore
 
 # Copy source code and build
 COPY . .
-RUN dotnet publish -c Release -o /app/publish
+RUN dotnet publish -c Release -o /app/publish /p:Version=${VERSION}
 
 # Runtime stage
 FROM mcr.microsoft.com/dotnet/aspnet:10.0-preview AS runtime
+ARG VERSION=0.0.0-dev
 WORKDIR /app
 
+# OCI Labels
+LABEL org.opencontainers.image.title="PaperlessMCP"
+LABEL org.opencontainers.image.description="Model Context Protocol server for Paperless-ngx"
+LABEL org.opencontainers.image.version="${VERSION}"
+LABEL org.opencontainers.image.source="https://github.com/barryw/PaperlessMCP"
+LABEL org.opencontainers.image.licenses="MIT"
+
 # Copy published application
 COPY --from=build /app/publish .
 
@@ -24,9 +33,5 @@ ENV MCP_PORT=5000
 # Expose port for HTTP transport
 EXPOSE 5000
 
-# Health check
-HEALTHCHECK --interval=30s --timeout=10s --start-period=5s --retries=3 \
-    CMD curl -f http://localhost:5000/mcp || exit 1
-
 # Run the application (HTTP mode by default)
 ENTRYPOINT ["dotnet", "PaperlessMCP.dll"]