feat: add ngit issue list command

Non-interactive listing of NIP-34 issues (kind 1621) with status
resolution, hashtag display, and detail view.

- get_issues_from_cache: fetch GitIssue events from local cache by repo
  coordinate, mirroring get_proposals_and_revisions_from_cache
- ngit issue list: table output of ID, status, title and hashtags at end
  of each row; status resolved via existing get_status() logic
- --status: comma-separated filter (open,draft,closed,applied; default: open)
- --hashtag: comma-separated label filter (case-insensitive, OR match)
- --json: machine-readable output including hashtags and description
- --offline: skip network fetch, use local cache only
- <id>: optional positional argument (hex event-id or nevent) to show
  full details of a specific issue including body content

1 files changed, 1 insertions, 0 deletions

diff --git a/src/bin/ngit/sub_commands/mod.rs b/src/bin/ngit/sub_commands/mod.rs
index d132240..d864391 100644
--- a/src/bin/ngit/sub_commands/mod.rs
+++ b/src/bin/ngit/sub_commands/mod.rs
@@ -3,6 +3,7 @@ pub mod checkout;
 pub mod create;
 pub mod export_keys;
 pub mod init;
+pub mod issue_list;
 pub mod list;
 pub mod login;
 pub mod logout;