internal/workflow + cli：gitea.py 工作流命令 Go 化（#6）

- internal/workflow：Client 介面＋判定語義（最後留言、作者/審核者跟進、
  assignee 交集、最久未更新優先），含假 client 單元測試
- internal/workflow/giteaapi.go：以 internal/gitea（#5）實作 Client
- internal/cli：註冊 whoami/orgs/members/mine/pulls/next；全域選項允許
  出現在命令之後；結束碼 0/2/3
- 與 gitea.py 交叉驗證：next/mine/pulls/members(--has-work) 拾取一致
- 依 #5 分支 feature/issue5-gitea-client 為基底

internal/workflow/giteaapi.go

@@ -0,0 +1,124 @@
+// giteaapi.go — 以 internal/gitea 的 HTTP 用戶端實作 workflow.Client。
+//
+// 端點與查詢參數對照 gitea.py：清單一律帶 limit 分頁（ListAll 固定 50）；
+// issues 端點帶 type=issues（排除 PR）與 state=open；pulls 帶 state=open。
+package workflow
+
+import (
+	"context"
+	"errors"
+	"net/url"
+	"strconv"
+
+	"gitea.alterminal.com/alterminal/teai/internal/gitea"
+)
+
+// errNoUsername 表示 /user 回應中找不到帳號名（伺服端回應異常）。
+var errNoUsername = errors.New("gitea: GET /user: response has no username")
+
+// APIClient 是 Client 介面的 HTTP 實作，包裝 internal/gitea.Client。
+type APIClient struct {
+	Client *gitea.Client
+}
+
+// 確認 APIClient 實作 Client 介面（編譯期檢查）。
+var _ Client = (*APIClient)(nil)
+
+func (a *APIClient) CurrentUser() (string, error) {
+	var u User
+	if err := a.Client.GetJSON(context.Background(), "/user", &u); err != nil {
+		return "", err
+	}
+	name := u.Name()
+	if name == "" {
+		return "", errNoUsername
+	}
+	return name, nil
+}
+
+func (a *APIClient) ListOrgs() ([]string, error) {
+	var orgs []Org
+	if err := a.Client.ListAll(context.Background(), "/user/orgs", gitea.ListOptions{}, &orgs); err != nil {
+		return nil, err
+	}
+	names := make([]string, 0, len(orgs))
+	for _, o := range orgs {
+		if n := o.Account(); n != "" {
+			names = append(names, n)
+		}
+	}
+	return names, nil
+}
+
+func (a *APIClient) ListTeams(org string) ([]Team, error) {
+	var teams []Team
+	path := "/orgs/" + url.PathEscape(org) + "/teams"
+	if err := a.Client.ListAll(context.Background(), path, gitea.ListOptions{}, &teams); err != nil {
+		return nil, err
+	}
+	return teams, nil
+}
+
+func (a *APIClient) ListTeamMembers(teamID int64) ([]string, error) {
+	var users []User
+	path := "/teams/" + strconv.FormatInt(teamID, 10) + "/members"
+	if err := a.Client.ListAll(context.Background(), path, gitea.ListOptions{}, &users); err != nil {
+		return nil, err
+	}
+	names := make([]string, 0, len(users))
+	for i := range users {
+		if n := users[i].Name(); n != "" {
+			names = append(names, n)
+		}
+	}
+	return names, nil
+}
+
+func (a *APIClient) ListOrgRepos(org string) ([]Repo, error) {
+	var repos []Repo
+	path := "/orgs/" + url.PathEscape(org) + "/repos"
+	if err := a.Client.ListAll(context.Background(), path, gitea.ListOptions{}, &repos); err != nil {
+		return nil, err
+	}
+	return repos, nil
+}
+
+func (a *APIClient) ListIssues(owner, repo string) ([]Issue, error) {
+	var issues []Issue
+	path := "/repos/" + url.PathEscape(owner) + "/" + url.PathEscape(repo) + "/issues"
+	opts := gitea.ListOptions{Extra: url.Values{
+		"type":  {"issues"},
+		"state": {"open"},
+	}}
+	if err := a.Client.ListAll(context.Background(), path, opts, &issues); err != nil {
+		return nil, err
+	}
+	// /issues 也會回傳 PR（帶 pull_request 欄位）；一律排除。
+	out := make([]Issue, 0, len(issues))
+	for i := range issues {
+		if issues[i].PullRequest == nil {
+			out = append(out, issues[i])
+		}
+	}
+	return out, nil
+}
+
+func (a *APIClient) ListPulls(owner, repo string) ([]PullRequest, error) {
+	var pulls []PullRequest
+	path := "/repos/" + url.PathEscape(owner) + "/" + url.PathEscape(repo) + "/pulls"
+	opts := gitea.ListOptions{Extra: url.Values{"state": {"open"}}}
+	if err := a.Client.ListAll(context.Background(), path, opts, &pulls); err != nil {
+		return nil, err
+	}
+	return pulls, nil
+}
+
+func (a *APIClient) ListComments(owner, repo string, number int64) ([]Comment, error) {
+	var comments []Comment
+	path := "/repos/" + url.PathEscape(owner) + "/" + url.PathEscape(repo) +
+		"/issues/" + strconv.FormatInt(number, 10) + "/comments"
+	if err := a.Client.ListAll(context.Background(), path, gitea.ListOptions{}, &comments); err != nil {
+		return nil, err
+	}
+	return comments, nil
+}