Add MCP server, note mutation endpoint, and updated_at tracking (v3.0.0)

New MCP server (mcp/) exposes kb operations as native MCP tools over
Streamable HTTP with Bearer token auth. Supports collections via tag
conventions, chunked file uploads, and agent-side search patterns.

Engine gains PATCH /api/v1/notes/{id} for in-place note updates with
transactional re-chunk/re-embed, and updated_at column on documents.

Go client adds updatenote command and Patch HTTP method.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

release-engine.sh

@@ -163,6 +163,22 @@ run docker build -t "$CPU_IMAGE" -t "$CPU_LATEST" -f "$ENGINE_DIR/Dockerfile.cpu
 
 echo ""
 
+#──────────────────────────────────────────────────────────────────────
+# 3b. Build Docker MCP server image
+#──────────────────────────────────────────────────────────────────────
+MCP_DIR="$SCRIPT_DIR/mcp"
+
+if [[ -f "$MCP_DIR/Dockerfile" ]]; then
+    echo "==> Building Docker MCP server image ($VERSION)"
+
+    MCP_IMAGE="${IMAGE_BASE}/mcp:${DOCKER_TAG}"
+    MCP_LATEST="${IMAGE_BASE}/mcp:latest"
+
+    run docker build -t "$MCP_IMAGE" -t "$MCP_LATEST" -f "$MCP_DIR/Dockerfile" "$MCP_DIR"
+
+    echo ""
+fi
+
 #──────────────────────────────────────────────────────────────────────
 # 4. Commit, tag, and push
 #──────────────────────────────────────────────────────────────────────
@@ -196,6 +212,12 @@ docker pull ${ROCM_IMAGE}
 
 # CPU only
 docker pull ${CPU_IMAGE}
+\`\`\`
+
+## MCP server
+
+\`\`\`bash
+docker pull ${MCP_IMAGE:-${IMAGE_BASE}/mcp:${DOCKER_TAG}}
 \`\`\`"
 
 if [[ "$FORGE" == "gh" ]]; then
@@ -224,6 +246,11 @@ run docker push "$ROCM_LATEST"
 run docker push "$CPU_IMAGE"
 run docker push "$CPU_LATEST"
 
+if [[ -n "${MCP_IMAGE:-}" ]]; then
+    run docker push "$MCP_IMAGE"
+    run docker push "$MCP_LATEST"
+fi
+
 echo ""
 echo "==> Release $GIT_TAG complete!"
 echo ""
@@ -231,3 +258,6 @@ echo "    Images:"
 echo "      $NVIDIA_IMAGE"
 echo "      $ROCM_IMAGE"
 echo "      $CPU_IMAGE"
+if [[ -n "${MCP_IMAGE:-}" ]]; then
+    echo "      $MCP_IMAGE"
+fi