Add Yesterday and subcommand aliases

When showing current threads, create an alias for 'Yesterday' to make
it visually easier for users to find a thread when they have many of
them. Additionally, allow users to save on typing with command
aliases. e.g. instead of 'archive' accept 'a' if there are no other
subcommands that start with an 'a'.

cmd/gptcli/main.go

@@ -520,9 +520,13 @@ func lsThreadsMain(ctx context.Context, gptCliCtx *GptCliContext,
 		aTime := t.AccessTime.Format("01/02/2006 03:04pm")
 		mTime := t.ModTime.Format("01/02/2006 03:04pm")
 		today := time.Now().UTC().Truncate(24 * time.Hour).Format("01/02/2006")
+		yesterday := time.Now().UTC().Add(-24 * time.Hour).Truncate(24 * time.Hour).Format("01/02/2006")
 		cTime = strings.ReplaceAll(cTime, today, "Today")
 		aTime = strings.ReplaceAll(aTime, today, "Today")
 		mTime = strings.ReplaceAll(mTime, today, "Today")
+		cTime = strings.ReplaceAll(cTime, yesterday, "Yesterday")
+		aTime = strings.ReplaceAll(aTime, yesterday, "Yesterday")
+		mTime = strings.ReplaceAll(mTime, yesterday, "Yesterday")
 
 		fmt.Printf(rowFmt, idx+1, aTime, mTime, cTime, t.Name)
 	}
@@ -1081,6 +1085,34 @@ func splitBlocks(text string) []string {
 	return blocks
 }
 
+func (gptCliCtx *GptCliContext) getSubCmd(
+	cmdOrPrompt string) func(context.Context, *GptCliContext, []string) error {
+
+	subCmdFunc, ok := subCommandTab[cmdOrPrompt]
+	if ok {
+		return subCmdFunc
+	}
+	if gptCliCtx.curThreadNum != 0 {
+		return nil
+	} // else we're not in a current thread; find closest match to allow
+	// aliasing. e.g. allow user to type 'a' instead of 'archive' if there's
+	// no other subcommand that starts with 'a'.
+
+	var subCmdFound string
+	for k, _ := range subCommandTab {
+		if strings.HasPrefix(k, cmdOrPrompt) {
+			if subCmdFound != "" {
+				// ambiguous
+				return nil
+			}
+
+			subCmdFound = k
+		}
+	}
+
+	return subCommandTab[subCmdFound]
+}
+
 func main() {
 	checkAndPrintUpgradeWarning()
 
@@ -1106,8 +1138,8 @@ func main() {
 		}
 		cmdArgs := strings.Split(fullCmdOrPrompt, " ")
 		cmdOrPrompt = cmdArgs[0]
-		subCmdFunc, ok := subCommandTab[cmdOrPrompt]
-		if !ok {
+		subCmdFunc := gptCliCtx.getSubCmd(cmdOrPrompt)
+		if subCmdFunc == nil {
 			if gptCliCtx.curThreadNum == 0 {
 				fmt.Fprintf(os.Stderr, "gptcli: Unknown command %v. Try	'help'.\n",
 					cmdOrPrompt)