refactor: reuse the existing service and rendering helpers

services.IsNotFound replaces the hand-rolled 404 checks, convertPage
the copied page conversions and lastPathNumber the comment's own
number parser. The List wrappers around ListPage of releases,
branches, wiki pages, secrets and variables go, pull request filters
resolve milestones through Milestones.FindOne like issues, and
localFlagsChanged, boolOrder, Cell.Render, stateBadge and dueText
replace their copies.

Signed-off-by: bircni <bircni@icloud.com>

internal/app/pull_edit.go

@@ -85,7 +85,7 @@ pull request, or mark it as a draft or ready for review.`, Annotations: pullArgu
 			var none int64
 			opts.Milestone = &none
 		case milestone != "":
-			id, err := milestoneFilter(cmd.Context(), t, milestone)
+			id, err := milestoneID(cmd, t, milestone)
 			if err != nil {
 				return err
 			}