Add Go runtime to serena-mcp-server container (#703)

Container had `gopls` (Go LSP) but was missing the Go runtime itself.
Serena needs both for Go code analysis and compilation.

## Changes

- **Dockerfile**: Added `golang-go` to apt-get install, preserving
existing cleanup steps
- **BUILD_NOTES.md**: Documented the addition

Result: Go 1.24.4 runtime now available alongside gopls v0.17.1.
Container size 912MB with proper apt cache cleanup (16K remaining).

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Author: lpcox

containers/serena-mcp-server/BUILD_NOTES.md

@@ -10,6 +10,14 @@ The Serena MCP server container Dockerfile has been created with support for:
 
 ## Recent Fixes
 
+### Go Runtime Re-added (2026-02-05)
+Re-added Go runtime to the container to support Go code analysis:
+- **Problem**: The Dockerfile only installed `gopls` (Go LSP) but not the Go runtime itself
+- **Solution**: Added `golang-go` package back to apt-get install with proper cleanup
+- **Impact**: Container now includes both Go runtime and gopls for complete Go support
+- **Testing**: The `go version` command now works, and Go code can be compiled/executed
+- **Image Size**: Cleanup steps ensure minimal impact on image size
+
 ### PATH Configuration Fix (2026-01-18)
 Fixed an issue where the `go` command was not found in the container's PATH during runtime:
 - **Problem**: Line 40 of the Dockerfile explicitly set `/usr/bin` in the PATH, which was redundant and potentially caused PATH resolution issues

containers/serena-mcp-server/Dockerfile

@@ -24,11 +24,13 @@ WORKDIR /app
 # - git: required for some Serena operations
 # - nodejs/npm: for TypeScript language server
 # - ca-certificates: for HTTPS
+# - golang-go: Go runtime for Go code analysis
 RUN apt-get update && apt-get install -y --no-install-recommends \
     git \
     nodejs \
     npm \
     ca-certificates \
+    golang-go \
     && rm -rf /var/lib/apt/lists/* \
     && apt-get clean