refactor(issue,pr): trim help, restating comments and single-use helpers

Cut issue, pr, label, milestone and comment examples to at most three, drop
doc comments that only restate the name, fold the comment and attachment
argument lookups into one closure each, and inline label helpers with one
caller.

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

internal/app/pull_mutations.go

@@ -71,7 +71,6 @@ func (a *application) addPullMutations(group *cobra.Command) {
 	group.AddCommand(a.pullCreateCommand(), a.pullStateCommand(true), a.pullStateCommand(false), a.pullDiffCommand(), a.pullReviewCommand(), a.pullMergeCommand())
 }
 
-// pullStateCommand builds tea pr close, or tea pr reopen when closing is false.
 func (a *application) pullStateCommand(closing bool) *cobra.Command {
 	verb, done, state := "reopen", "Reopened", "open"
 	if closing {
@@ -252,7 +251,6 @@ var mergeVerbs = map[string]string{
 	"merge": "Merged", "rebase": "Rebased and merged", "rebase-merge": "Rebased and merged", "squash": "Squashed and merged", "fast-forward-only": "Merged",
 }
 
-// mergeMethods are the merge styles in Gitea's order.
 var mergeMethods = []string{"merge", "rebase", "rebase-merge", "squash", "fast-forward-only"}
 
 func (a *application) pullMergeCommand() *cobra.Command {