Slice 10: create_pr (open a pull request)

forge CreatePullRequest (Gitea; empty base resolves to the repo default branch). Service CreatePR records a pr-created event. HTTP POST /api/repo/pr/create; MCP tool create_pr; <pr-list> New pull request button (head = selected repo current branch, base = default). Live-tested end-to-end: app create_pr opened a real PR (base auto-resolved), listed, then cleaned up; main untouched.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

internal/service/service.go

@@ -137,6 +137,22 @@ func (s *Service) ForgePRs(ctx context.Context, repoPath string) ([]forge.PullRe
 	return s.forge.ListPullRequests(ctx, owner, repo)
 }
 
+// CreatePR opens a pull request from head into base (empty base = the repo's
+// default branch) and records the action. The head branch must already exist on
+// the remote (push it first).
+func (s *Service) CreatePR(ctx context.Context, actor activity.Actor, repoPath, head, base, title, body string) (forge.PullRequest, error) {
+	owner, repo, err := s.resolveForge(ctx, repoPath)
+	if err != nil {
+		return forge.PullRequest{}, err
+	}
+	pr, err := s.forge.CreatePullRequest(ctx, owner, repo, forge.NewPR{Head: head, Base: base, Title: title, Body: body})
+	if err != nil {
+		return forge.PullRequest{}, err
+	}
+	s.feed.Record(actor, "pr-created", filepath.Clean(repoPath), fmt.Sprintf("PR #%d %s → %s", pr.Number, pr.Head, pr.Base))
+	return pr, nil
+}
+
 // MergeAndCleanup merges a PR and deletes its branch, then records the action.
 // The caller is responsible for confirming with the user first (§1.4); actor
 // distinguishes a UI action (user) from an MCP one (claude).