Replace implicit note shorthand with explicit addnote command and split README

Two changes:

1. structured-add-commands: The implicit note shorthand (kb "text") caused
   accidental note creation from mistyped commands. Replaced with explicit
   kb addnote <text> command. Root command reverts to standard Cobra
   behaviour. Updated examples, tests, SKILL.md, and specs.

2. split-readme-developer-docs: Moved build-from-source instructions, release
   process, API reference, and ROCm migration notes from README.md into a
   new DEVELOPER.md. README now links to DEVELOPER.md for dev workflows.

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

client/cmd/root.go

@@ -3,7 +3,6 @@ package cmd
 import (
 	"fmt"
 	"os"
-	"strings"
 
 	"github.com/kb-search/kb/internal/api"
 	"github.com/kb-search/kb/internal/config"
@@ -23,10 +22,9 @@ var (
 )
 
 var rootCmd = &cobra.Command{
-	Use:   "kb [\"note text\" | command]",
+	Use:   "kb [command]",
 	Short: "kb-search CLI client",
 	Long:  "A CLI client for the kb-search v2 engine API.\nRun 'kb examples' for common usage patterns.",
-	Args: cobra.ArbitraryArgs,
 	PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
 		if err := config.Load(); err != nil {
 			return err
@@ -34,44 +32,14 @@ var rootCmd = &cobra.Command{
 		config.ApplyFlags(flagEngine, flagFormat, flagAPIKey)
 		return nil
 	},
-	RunE: func(cmd *cobra.Command, args []string) error {
-		if len(args) == 0 {
-			return cmd.Help()
-		}
-		if len(args) == 1 {
-			return fmt.Errorf("unknown command %q\nTo add a note, use: kb \"%s ...\" or pass multiple words", args[0], args[0])
-		}
-		note := strings.Join(args, " ")
-		tags, _ := cmd.Flags().GetString("tags")
-		client := api.NewClient()
-		return submitNote(client, note, tags)
-	},
 }
 
 func init() {
 	api.SetVersionInfo(Version, MinEngineVersion)
 	rootCmd.Version = Version
-	rootCmd.SetUsageTemplate(`Quick note taking (must be more than one word):
-  kb "note text here" [flags]
-
-Normal usage:
-  kb [command] [flags]{{if .HasAvailableSubCommands}}
-
-Available Commands:{{range .Commands}}{{if (or .IsAvailableCommand (eq .Name "help"))}}
-  {{rpad .Name .NamePadding }} {{.Short}}{{end}}{{end}}{{end}}{{if .HasAvailableLocalFlags}}
-
-Flags:
-{{.LocalFlags.FlagUsages | trimTrailingWhitespaces}}{{end}}{{if .HasAvailableInheritedFlags}}
-
-Global Flags:
-{{.InheritedFlags.FlagUsages | trimTrailingWhitespaces}}{{end}}
-
-Use "{{.CommandPath}} [command] --help" for more information about a command.
-`)
 	rootCmd.PersistentFlags().StringVar(&flagEngine, "engine", "", "engine API URL")
 	rootCmd.PersistentFlags().StringVar(&flagFormat, "format", "", "output format (human|json)")
 	rootCmd.PersistentFlags().StringVar(&flagAPIKey, "api-key", "", "API key for authentication")
-	rootCmd.Flags().String("tags", "", "tags for note shorthand (comma-separated)")
 }
 
 // Execute runs the root command.