Add agentpr and watchpr CLI tools

agentpr manages PRs/comments/whoami as unkin-agent (Vault AppRole -> gitea creds
-> Gitea API), fixing tea's post-as-Ben default. watchpr polls PRs and alerts
only on merge/close, human comment, CI failure, or lost mergeability.

- cobra multi-binary layout mirroring node-lookup (cmd/ + internal/)
- Makefile (build, patch|minor|major, completions, rpm), nfpm RPM with both
  binaries + bash/zsh/fish completions, woodpecker CI publishing to rpm-internal
- unit tests for parsing, meaningful-change detection, and the Vault+Gitea client

cmd/agentpr/main.go

@@ -0,0 +1,165 @@
+// Command agentpr manages Gitea pull requests and comments as the unkin-agent
+// user. It obtains a scoped Gitea token from Vault (AppRole login, then reads
+// gitea/creds/unkin-agent) so actions are attributed to the agent rather than
+// to whoever runs the tool.
+//
+//	agentpr pr create --repo owner/repo --base main --head feature --title T --body B
+//	agentpr pr comment --repo owner/repo --pr 12 --body "..."
+//	agentpr whoami
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"git.unkin.net/unkin/agent-tools/internal/agent"
+
+	"github.com/spf13/cobra"
+)
+
+var version = "dev"
+
+func main() {
+	root := &cobra.Command{
+		Use:          "agentpr",
+		Short:        "Manage Gitea PRs and comments as the unkin-agent user.",
+		Long:         "agentpr manages Gitea pull requests and comments as unkin-agent, using a\nGitea token minted from Vault (AppRole login + gitea/creds/unkin-agent).",
+		Version:      version,
+		SilenceUsage: true,
+	}
+	root.SetVersionTemplate("{{.Version}}\n")
+
+	root.AddCommand(newPRCmd(), newWhoamiCmd(), newVersionCmd())
+
+	if err := root.Execute(); err != nil {
+		os.Exit(1)
+	}
+}
+
+// client mints a Gitea token via Vault and returns a ready client.
+func client() (*agent.GiteaClient, error) {
+	token, err := agent.GiteaToken()
+	if err != nil {
+		return nil, err
+	}
+	return agent.NewGiteaClient(token), nil
+}
+
+func newPRCmd() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "pr",
+		Short: "Create PRs and post PR comments",
+	}
+	cmd.AddCommand(newPRCreateCmd(), newPRCommentCmd())
+	return cmd
+}
+
+func newPRCreateCmd() *cobra.Command {
+	var repo, base, head, title, body string
+	cmd := &cobra.Command{
+		Use:          "create",
+		Short:        "Open a pull request",
+		SilenceUsage: true,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			owner, name, err := agent.ParseRepo(repo)
+			if err != nil {
+				return err
+			}
+			if base == "" || head == "" || title == "" {
+				return fmt.Errorf("--base, --head and --title are required")
+			}
+			c, err := client()
+			if err != nil {
+				return err
+			}
+			pr, err := c.CreatePR(owner+"/"+name, agent.CreatePROptions{
+				Base:  base,
+				Head:  head,
+				Title: title,
+				Body:  body,
+			})
+			if err != nil {
+				return err
+			}
+			fmt.Printf("#%d %s\n", pr.Number, pr.HTMLURL)
+			return nil
+		},
+	}
+	f := cmd.Flags()
+	f.StringVar(&repo, "repo", "", "Repository as owner/repo (required)")
+	f.StringVar(&base, "base", "", "Base branch (required)")
+	f.StringVar(&head, "head", "", "Head branch (required)")
+	f.StringVar(&title, "title", "", "PR title (required)")
+	f.StringVar(&body, "body", "", "PR body")
+	_ = cmd.MarkFlagRequired("repo")
+	return cmd
+}
+
+func newPRCommentCmd() *cobra.Command {
+	var repo, body string
+	var pr int
+	cmd := &cobra.Command{
+		Use:          "comment",
+		Short:        "Post a comment on a pull request",
+		SilenceUsage: true,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			owner, name, err := agent.ParseRepo(repo)
+			if err != nil {
+				return err
+			}
+			if pr <= 0 {
+				return fmt.Errorf("--pr must be a positive PR number")
+			}
+			if body == "" {
+				return fmt.Errorf("--body is required")
+			}
+			c, err := client()
+			if err != nil {
+				return err
+			}
+			cm, err := c.CreateComment(owner+"/"+name, pr, body)
+			if err != nil {
+				return err
+			}
+			fmt.Printf("comment %d posted on %s/%s#%d\n", cm.ID, owner, name, pr)
+			return nil
+		},
+	}
+	f := cmd.Flags()
+	f.StringVar(&repo, "repo", "", "Repository as owner/repo (required)")
+	f.IntVar(&pr, "pr", 0, "PR number (required)")
+	f.StringVar(&body, "body", "", "Comment body (required)")
+	_ = cmd.MarkFlagRequired("repo")
+	_ = cmd.MarkFlagRequired("pr")
+	_ = cmd.MarkFlagRequired("body")
+	return cmd
+}
+
+func newWhoamiCmd() *cobra.Command {
+	return &cobra.Command{
+		Use:          "whoami",
+		Short:        "Print the authenticated Gitea login (should be unkin-agent)",
+		SilenceUsage: true,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			c, err := client()
+			if err != nil {
+				return err
+			}
+			u, err := c.Whoami()
+			if err != nil {
+				return err
+			}
+			fmt.Println(u.Login)
+			return nil
+		},
+	}
+}
+
+func newVersionCmd() *cobra.Command {
+	return &cobra.Command{
+		Use:          "version",
+		Short:        "Print the version",
+		Run:          func(cmd *cobra.Command, args []string) { fmt.Println(version) },
+		SilenceUsage: true,
+	}
+}