feat: implement core CLI packages and Phase 3 commands

- config: resolve binary dir, load/save .hf-config.json
- mode: detect padded-cell vs manual mode via pass_mgr
- client: HTTP client wrapper with auth header support
- passmgr: pass_mgr integration (get-secret, set, generate)
- output: human-readable + JSON output formatting with tables
- help: help and help-brief renderer for groups/commands
- commands: version, health, config (--url, --acc-mgr-token, show)
- auth: token resolution helper (padded-cell auto / manual explicit)
- main: command dispatcher with --json global flag support
- README: updated with current package layout and status

internal/output/output.go

@@ -0,0 +1,93 @@
+// Package output handles human-readable and JSON output formatting.
+package output
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"strings"
+)
+
+// JSONMode is true when --json flag is provided.
+var JSONMode bool
+
+// PrintJSON prints data as indented JSON to stdout.
+func PrintJSON(v interface{}) {
+	data, err := json.MarshalIndent(v, "", "  ")
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "error: cannot marshal JSON: %v\n", err)
+		os.Exit(1)
+	}
+	fmt.Println(string(data))
+}
+
+// PrintKeyValue prints a set of key-value pairs in human-readable format.
+func PrintKeyValue(pairs ...string) {
+	if len(pairs)%2 != 0 {
+		pairs = append(pairs, "")
+	}
+	maxKeyLen := 0
+	for i := 0; i < len(pairs); i += 2 {
+		if len(pairs[i]) > maxKeyLen {
+			maxKeyLen = len(pairs[i])
+		}
+	}
+	for i := 0; i < len(pairs); i += 2 {
+		fmt.Printf("%-*s  %s\n", maxKeyLen, pairs[i]+":", pairs[i+1])
+	}
+}
+
+// PrintTable prints a simple table with headers and rows.
+func PrintTable(headers []string, rows [][]string) {
+	if len(rows) == 0 {
+		fmt.Println("(no results)")
+		return
+	}
+	widths := make([]int, len(headers))
+	for i, h := range headers {
+		widths[i] = len(h)
+	}
+	for _, row := range rows {
+		for i, cell := range row {
+			if i < len(widths) && len(cell) > widths[i] {
+				widths[i] = len(cell)
+			}
+		}
+	}
+	// header
+	parts := make([]string, len(headers))
+	for i, h := range headers {
+		parts[i] = fmt.Sprintf("%-*s", widths[i], h)
+	}
+	fmt.Println(strings.Join(parts, "  "))
+	// separator
+	seps := make([]string, len(headers))
+	for i := range headers {
+		seps[i] = strings.Repeat("-", widths[i])
+	}
+	fmt.Println(strings.Join(seps, "  "))
+	// rows
+	for _, row := range rows {
+		parts := make([]string, len(headers))
+		for i := range headers {
+			cell := ""
+			if i < len(row) {
+				cell = row[i]
+			}
+			parts[i] = fmt.Sprintf("%-*s", widths[i], cell)
+		}
+		fmt.Println(strings.Join(parts, "  "))
+	}
+}
+
+// Error prints an error message to stderr and exits.
+func Error(msg string) {
+	fmt.Fprintln(os.Stderr, msg)
+	os.Exit(1)
+}
+
+// Errorf prints a formatted error message to stderr and exits.
+func Errorf(format string, args ...interface{}) {
+	fmt.Fprintf(os.Stderr, format+"\n", args...)
+	os.Exit(1)
+}