feat(subject): add pr/issue set-subject via NIP-32 kind-1985 labels

Adds the ability to update the displayed title of a PR or issue after
creation using a kind-1985 label event with the #subject namespace.
Only the author or a repository maintainer may set the subject. The
latest authorised event wins with tiebreak by lexicographically larger
event ID (NIP-1 replaceable event semantics). Branch names and commit
messages are never affected.

- Split get_labels() into process_labels() (additive #t) and
  process_subject() (replaceable-style #subject), with a shared
  get_labels_and_subject() entry point that processes both from a
  single pre-fetched slice of kind-1985 events
- All list/view/JSON display paths apply the subject override silently
- New ngit pr set-subject <id> --subject <text> command
- New ngit issue set-subject <id> --subject <text> command

1 files changed, 13 insertions, 1 deletions

diff --git a/src/bin/ngit/main.rs b/src/bin/ngit/main.rs
index 3686011..1dbf020 100644
--- a/src/bin/ngit/main.rs
+++ b/src/bin/ngit/main.rs
@@ -3,7 +3,7 @@
 #![cfg_attr(not(test), warn(clippy::expect_used))]
 
 use clap::Parser;
-use cli::{AccountCommands, CUSTOMISE_TEMPLATE, Cli, Commands, IssueCommands, PrCommands};
+use cli::{AccountCommands, Cli, Commands, IssueCommands, PrCommands, CUSTOMISE_TEMPLATE};
 
 mod cli;
 use ngit::{
@@ -138,6 +138,11 @@ async fn main() {
                     labels,
                     offline,
                 } => sub_commands::label::launch_pr_label(id, labels, *offline).await,
+                PrCommands::SetSubject {
+                    id,
+                    subject,
+                    offline,
+                } => sub_commands::set_subject::launch_pr_set_subject(id, subject, *offline).await,
             },
             Commands::Issue(args) => match &args.issue_command {
                 IssueCommands::List {
@@ -210,6 +215,13 @@ async fn main() {
                     labels,
                     offline,
                 } => sub_commands::label::launch_issue_label(id, labels, *offline).await,
+                IssueCommands::SetSubject {
+                    id,
+                    subject,
+                    offline,
+                } => {
+                    sub_commands::set_subject::launch_issue_set_subject(id, subject, *offline).await
+                }
             },
             Commands::Sync(args) => sub_commands::sync::launch(args).await,
         }