feat: pr approve/reject, repo migrate/template, secret stdin fix, docs

- fgj pr approve / pr reject: thin shortcuts over 'pr review --approve'
  and '--request-changes'. Reject requires a body.
- fgj repo migrate: wrap SDK MigrateRepo. Supports git, github, gitlab,
  gitea, gogs services; mirror mode with --mirror-interval; selective
  import (wiki/labels/milestones/issues/PRs/releases/LFS); auth via
  --auth-token or --auth-username/--auth-password. Defaults owner to
  the authenticated user.
- fgj repo create-from-template: wrap SDK CreateRepoFromTemplate with
  fine-grained --with-{content,topics,labels,webhooks,git-hooks,avatar}
  flags. Template is owner/name; new repo defaults to the current user.
- Rework 'fgj actions secret create' input. New cmd/secret_input.go
  resolves values from --body, --body-file (path or '-'), hidden TTY
  prompt via term.ReadPassword, or piped stdin. Trims trailing
  whitespace, rejects empty values. Replaces fmt.Scanln which broke on
  spaces/newlines and echoed input.
- CHANGELOG: v0.4.0 Unreleased section documenting all additions,
  changes, and development items.
- README: updated feature list with new commands.

cmd/repo_template.go

@@ -0,0 +1,113 @@
+package cmd
+
+import (
+	"fmt"
+	"strings"
+
+	"code.gitea.io/sdk/gitea"
+	"github.com/spf13/cobra"
+)
+
+var repoCreateFromTemplateCmd = &cobra.Command{
+	Use:     "create-from-template <template-owner/template-name> <new-name>",
+	Aliases: []string{"ct"},
+	Short:   "Create a repository from a template",
+	Long: `Scaffold a new repository based on an existing template repository.
+
+By default this copies only the default branch content. Pass --with-<kind>
+flags to include topics, labels, webhooks, git hooks, and other template
+metadata.`,
+	Example: `  # Create a new repo under your account from a template
+  fgj repo create-from-template org/template-name my-new-repo
+
+  # Target a specific owner and make it private
+  fgj repo create-from-template org/template-name new-repo --owner myorg --private
+
+  # Copy everything: content, topics, labels, webhooks, hooks, avatar
+  fgj repo create-from-template org/template-name new-repo \
+    --with-content --with-topics --with-labels \
+    --with-webhooks --with-git-hooks --with-avatar`,
+	Args: cobra.ExactArgs(2),
+	RunE: runRepoCreateFromTemplate,
+}
+
+func init() {
+	repoCmd.AddCommand(repoCreateFromTemplateCmd)
+
+	repoCreateFromTemplateCmd.Flags().String("owner", "", "Owner (user or org) for the new repository (defaults to you)")
+	repoCreateFromTemplateCmd.Flags().StringP("description", "d", "", "Description for the new repository")
+	repoCreateFromTemplateCmd.Flags().Bool("private", false, "Make the new repository private")
+	repoCreateFromTemplateCmd.Flags().Bool("with-content", true, "Include default branch content from the template")
+	repoCreateFromTemplateCmd.Flags().Bool("with-topics", false, "Include topics from the template")
+	repoCreateFromTemplateCmd.Flags().Bool("with-labels", false, "Include labels from the template")
+	repoCreateFromTemplateCmd.Flags().Bool("with-webhooks", false, "Include webhooks from the template")
+	repoCreateFromTemplateCmd.Flags().Bool("with-git-hooks", false, "Include git hooks from the template")
+	repoCreateFromTemplateCmd.Flags().Bool("with-avatar", false, "Include the template repo's avatar")
+
+	addJSONFlags(repoCreateFromTemplateCmd, "Output created repository as JSON")
+}
+
+func runRepoCreateFromTemplate(cmd *cobra.Command, args []string) error {
+	templateSlug := args[0]
+	newName := args[1]
+
+	parts := strings.SplitN(templateSlug, "/", 2)
+	if len(parts) != 2 || parts[0] == "" || parts[1] == "" {
+		return fmt.Errorf("template must be in owner/name format (got %q)", templateSlug)
+	}
+	templateOwner, templateName := parts[0], parts[1]
+
+	client, err := loadClient()
+	if err != nil {
+		return err
+	}
+
+	owner, _ := cmd.Flags().GetString("owner")
+	if owner == "" {
+		user, _, err := client.GetMyUserInfo()
+		if err != nil {
+			return fmt.Errorf("failed to resolve current user (pass --owner to override): %w", err)
+		}
+		owner = user.UserName
+	}
+
+	description, _ := cmd.Flags().GetString("description")
+	private, _ := cmd.Flags().GetBool("private")
+	withContent, _ := cmd.Flags().GetBool("with-content")
+	withTopics, _ := cmd.Flags().GetBool("with-topics")
+	withLabels, _ := cmd.Flags().GetBool("with-labels")
+	withWebhooks, _ := cmd.Flags().GetBool("with-webhooks")
+	withGitHooks, _ := cmd.Flags().GetBool("with-git-hooks")
+	withAvatar, _ := cmd.Flags().GetBool("with-avatar")
+
+	opt := gitea.CreateRepoFromTemplateOption{
+		Owner:       owner,
+		Name:        newName,
+		Description: description,
+		Private:     private,
+		GitContent:  withContent,
+		Topics:      withTopics,
+		Labels:      withLabels,
+		Webhooks:    withWebhooks,
+		GitHooks:    withGitHooks,
+		Avatar:      withAvatar,
+	}
+
+	ios.StartSpinner("Creating from template...")
+	repo, _, err := client.CreateRepoFromTemplate(templateOwner, templateName, opt)
+	ios.StopSpinner()
+	if err != nil {
+		return fmt.Errorf("template instantiation failed: %w", err)
+	}
+
+	if wantJSON(cmd) {
+		return outputJSON(cmd, repo)
+	}
+
+	cs := ios.ColorScheme()
+	fmt.Fprintf(ios.Out, "%s Created %s from template %s\n", cs.SuccessIcon(), repo.FullName, templateSlug)
+	if repo.HTMLURL != "" {
+		fmt.Fprintf(ios.Out, "  %s\n", repo.HTMLURL)
+	}
+	return nil
+}