v2 restructure: Go client, Docker engine, release tooling

- Remove v1 Python CLI (src/kb_search/, tests/, root pyproject.toml, uv.lock, .venv)
- Add Go client with cross-platform build (client/)
- Add FastAPI engine with NVIDIA and multi-stage ROCm Dockerfiles (engine/)
- Add VERSION files for client and engine, wired into builds
- Add release.sh for automated build, tag, release, and Docker push
- Update README with build/release docs and ROCm migration note
- Clean up .gitignore for v2 project structure

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

client/internal/output/format.go

@@ -0,0 +1,90 @@
+package output
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/kb-search/kb/internal/config"
+)
+
+// IsJSON returns true if the configured output format is "json".
+func IsJSON() bool {
+	return config.Get().DefaultFormat == "json"
+}
+
+// PrintJSON pretty-prints data as JSON to stdout.
+func PrintJSON(data interface{}) {
+	enc := json.NewEncoder(os.Stdout)
+	enc.SetIndent("", "  ")
+	_ = enc.Encode(data)
+}
+
+// PrintTable prints a simple aligned table with headers and rows.
+func PrintTable(headers []string, rows [][]string) {
+	if len(headers) == 0 {
+		return
+	}
+
+	// Calculate column widths
+	widths := make([]int, len(headers))
+	for i, h := range headers {
+		widths[i] = len(h)
+	}
+	for _, row := range rows {
+		for i := 0; i < len(row) && i < len(widths); i++ {
+			if len(row[i]) > widths[i] {
+				widths[i] = len(row[i])
+			}
+		}
+	}
+
+	// Print header
+	for i, h := range headers {
+		if i > 0 {
+			fmt.Print("  ")
+		}
+		fmt.Printf("%-*s", widths[i], h)
+	}
+	fmt.Println()
+
+	// Print separator
+	for i, w := range widths {
+		if i > 0 {
+			fmt.Print("  ")
+		}
+		fmt.Print(strings.Repeat("-", w))
+	}
+	fmt.Println()
+
+	// Print rows
+	for _, row := range rows {
+		for i := 0; i < len(headers); i++ {
+			if i > 0 {
+				fmt.Print("  ")
+			}
+			val := ""
+			if i < len(row) {
+				val = row[i]
+			}
+			fmt.Printf("%-*s", widths[i], val)
+		}
+		fmt.Println()
+	}
+}
+
+// PrintKeyValue prints aligned key-value pairs.
+func PrintKeyValue(pairs [][]string) {
+	maxKey := 0
+	for _, p := range pairs {
+		if len(p) >= 2 && len(p[0]) > maxKey {
+			maxKey = len(p[0])
+		}
+	}
+	for _, p := range pairs {
+		if len(p) >= 2 {
+			fmt.Printf("%-*s  %s\n", maxKey, p[0]+":", p[1])
+		}
+	}
+}