feat(label): add `ngit issue label` and `ngit pr label` commands

Publishes a NIP-32 kind-1985 label event referencing the target issue or
PR. Only the event author or a repository maintainer may apply labels.
Duplicate labels (already present via t-tags or prior kind-1985 events)
are silently skipped. The new event is saved to the local cache before
broadcasting so subsequent reads reflect the change immediately.

CLI:
  ngit issue label <id> --label <L> [--label <L>...]
  ngit pr label <id> --label <L> [--label <L>...]

1 files changed, 2 insertions, 0 deletions

diff --git a/skills/ngit/SKILL.md b/skills/ngit/SKILL.md
index 7621086..1436452 100644
--- a/skills/ngit/SKILL.md
+++ b/skills/ngit/SKILL.md
@@ -122,6 +122,7 @@ git push origin main      # push to nostr remote records the merge event
 ngit pr close <ID|nevent>
 ngit pr reopen <ID|nevent>
 ngit pr ready <ID|nevent>   # mark draft as ready for review
+ngit pr label <ID|nevent> --label bug --label enhancement
 ```
 
 ## Issues
@@ -138,6 +139,7 @@ ngit issue comment <ID|nevent> --body "Reproduced on v2.1"
 ngit issue comment <ID|nevent> --body "Thanks!" --reply-to <comment-ID|nevent>
 ngit issue close <ID|nevent>
 ngit issue reopen <ID|nevent>
+ngit issue label <ID|nevent> --label bug --label enhancement
 ```
 
 ## Account management