Fix gitea-mcp COPY path: use explicit GOBIN instead of guessing GOPATH default

golang:1.26-alpine uses GOPATH=/go (not /root/go), so the binary was
installed to /go/bin/gitea-mcp but the COPY looked at /root/go/bin/.
Set GOBIN=/usr/local/bin for a deterministic install location.

Also adds harness MCP server bundle to the image.

apps/harness/Dockerfile

@@ -1,4 +1,5 @@
 FROM golang:1.26-alpine AS gitea-mcp-builder
+ENV GOBIN=/usr/local/bin
 RUN go install gitea.com/gitea/gitea-mcp@latest
 
 FROM node:20-alpine AS base
@@ -38,7 +39,7 @@ RUN curl -fsSL https://opencode.ai/install | sh || \
     echo "WARN: opencode install failed, skipping"
 
 # MCP servers: Gitea (Go binary from builder stage)
-COPY --from=gitea-mcp-builder /root/go/bin/gitea-mcp /usr/local/bin/gitea-mcp
+COPY --from=gitea-mcp-builder /usr/local/bin/gitea-mcp /usr/local/bin/gitea-mcp
 
 # MCP servers: Node.js packages (pre-installed to avoid npx cold starts)
 RUN npm install -g \
@@ -57,6 +58,9 @@ COPY --from=builder /app/apps/harness/public ./apps/harness/public
 COPY --from=builder --chown=nextjs:nodejs /app/apps/harness/.next/standalone ./
 COPY --from=builder --chown=nextjs:nodejs /app/apps/harness/.next/static ./apps/harness/.next/static
 
+# Harness MCP server (self-contained bundle for agent→harness communication)
+COPY --from=builder /app/apps/harness/dist/mcp-server.mjs ./apps/harness/dist/mcp-server.mjs
+
 # PTY server dependencies + custom server
 COPY --from=builder /app/node_modules/.pnpm/node-pty*/node_modules/node-pty ./node_modules/node-pty
 COPY --from=builder /app/node_modules/.pnpm/ws*/node_modules/ws ./node_modules/ws