refactor: add terminal output and forms package (#1124)

- `internal/terminal`: streams and the prompting policy, interactive forms (issue, PR, review, merge, milestone), editor / pager / browser launching, JSON and `--jq` output.
- An aligned table renderer and a record renderer for human output; both strip control and escape characters from server-supplied text so titles and bodies cannot inject terminal sequences.

Reviewed-on: https://gitea.com/gitea/tea/pulls/1124
Reviewed-by: TheFox0x7 <95654+thefox0x7@noreply.gitea.com>

internal/terminal/issue_edit_form.go

@@ -0,0 +1,89 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package terminal
+
+import (
+	"context"
+	"slices"
+	"strings"
+	"time"
+
+	"charm.land/huh/v2"
+)
+
+// IssueEditFormChoices supplies current issue values and selectable options for edit.
+// Current values missing from the options stay selectable.
+type IssueEditFormChoices struct {
+	Title, Body        string
+	Assignees          []string
+	Milestone          *IssueMilestoneChoice
+	Labels             []IssueLabelChoice
+	Deadline           *time.Time
+	CanPush            bool
+	AvailableAssignees []string
+	Milestones         []IssueMilestoneChoice
+	AvailableLabels    []IssueLabelChoice
+	EditBody           BodyEditor
+}
+
+// IssueEditFormValues holds interactively edited issue fields. Deadline is set
+// only when the due date changed.
+type IssueEditFormValues struct {
+	Title, Body    string
+	Assignees      []string
+	Milestone      int64
+	ClearMilestone bool
+	Labels         []int64
+	Deadline       *time.Time
+	ClearDeadline  bool
+	Draft          Draft
+}
+
+// IssueEditForm collects interactive issue edit input.
+type IssueEditForm interface {
+	EditIssue(context.Context, IssueEditFormChoices) (IssueEditFormValues, error)
+}
+
+// EditIssue runs the interactive issue edit form on stderr, seeded with the current values.
+func (p *FormPrompter) EditIssue(ctx context.Context, choices IssueEditFormChoices) (IssueEditFormValues, error) {
+	deadline := ""
+	if choices.Deadline != nil && !choices.Deadline.IsZero() {
+		// Keep the server's offset: converting to UTC can move the date by a day.
+		deadline = choices.Deadline.Format(time.DateOnly)
+	}
+	fields := issueFields{title: choices.Title, body: choices.Body, deadline: deadline, assignees: choices.Assignees}
+	milestones := choices.Milestones
+	if choices.Milestone != nil {
+		fields.milestone, milestones = choices.Milestone.ID, withCurrent(milestones, *choices.Milestone)
+	}
+	for _, label := range choices.Labels {
+		fields.labels = append(fields.labels, label.ID)
+	}
+	groups := fields.groups(choices.EditBody, choices.CanPush, withCurrent(choices.AvailableAssignees, choices.Assignees...), milestones, withCurrent(choices.AvailableLabels, choices.Labels...))
+	if err := p.runForm(ctx, huh.NewForm(groups...)); err != nil {
+		return IssueEditFormValues{}, err
+	}
+	values := IssueEditFormValues{Title: strings.TrimSpace(fields.title), Assignees: fields.assignees, Milestone: fields.milestone, Labels: fields.labels}
+	values.ClearMilestone = fields.milestone == 0 && choices.Milestone != nil
+	var err error
+	if values.Body, values.Draft, err = editBody(ctx, choices.EditBody, fields.body); err != nil {
+		return values, err
+	}
+	if strings.TrimSpace(fields.deadline) == deadline {
+		return values, nil
+	}
+	values.Deadline, err = parseDueDate(fields.deadline)
+	values.ClearDeadline = values.Deadline == nil && deadline != ""
+	return values, err
+}
+
+// withCurrent appends current values missing from options; selects drop values they do not offer.
+func withCurrent[T comparable](options []T, current ...T) []T {
+	for _, value := range current {
+		if !slices.Contains(options, value) {
+			options = append(slices.Clip(options), value)
+		}
+	}
+	return options
+}