feat(cover-note): add kind-1624 cover notes for PRs, patches, and issues

Implements experimental kind-1624 cover note events:

- KIND_COVER_NOTE constant and process_cover_note() in git_events.rs;
  replaceable semantics (latest created_at, hex-id tiebreak), author or
  maintainer only
- kind-1624 events fetched alongside labels in the fetch pipeline;
  cover_notes count added to FetchReport display
- ngit pr/issue view: cover note displayed in place of description with
  a clear 'Cover Note:' header; maintainer-authored notes identify the
  author; original description shown only with --comments; cover_note
  object included in --json output
- ngit pr set-cover-note / ngit issue set-cover-note: publish a
  kind-1624 event; nostr: mentions in --body converted to q/p tags via
  tags_from_content (same rules as issue --body)
- Fix pre-existing clippy::too_many_lines on repo/mod.rs show_info

1 files changed, 34 insertions, 1 deletions

diff --git a/src/bin/ngit/cli.rs b/src/bin/ngit/cli.rs
index 8660b60..d558525 100644
--- a/src/bin/ngit/cli.rs
+++ b/src/bin/ngit/cli.rs
@@ -160,7 +160,8 @@ pub struct RepoSubCommandArgs {
     /// Use local cache only, skip network fetch
     #[arg(long)]
     pub offline: bool,
-    /// Output repository info as JSON; `is_nostr_repo` is false when not in a nostr repository
+    /// Output repository info as JSON; `is_nostr_repo` is false when not in a
+    /// nostr repository
     #[arg(long)]
     pub json: bool,
 }
@@ -347,6 +348,22 @@ pub enum PrCommands {
         #[arg(long)]
         offline: bool,
     },
+    /// set or update the cover note for a PR (author or maintainer only)
+    ///
+    /// A cover note is a markdown body that replaces the displayed description.
+    /// nostr: mentions in --body are converted to q/p tags automatically.
+    #[command(name = "set-cover-note")]
+    SetCoverNote {
+        /// Proposal event-id (hex) or nevent (bech32)
+        #[arg(value_name = "ID|nevent")]
+        id: String,
+        /// Markdown body for the cover note
+        #[arg(long)]
+        body: String,
+        /// Use local cache only, skip network fetch
+        #[arg(long)]
+        offline: bool,
+    },
 }
 
 // ---------------------------------------------------------------------------
@@ -487,6 +504,22 @@ pub enum IssueCommands {
         #[arg(long)]
         offline: bool,
     },
+    /// set or update the cover note for an issue (author or maintainer only)
+    ///
+    /// A cover note is a markdown body that replaces the displayed description.
+    /// nostr: mentions in --body are converted to q/p tags automatically.
+    #[command(name = "set-cover-note")]
+    SetCoverNote {
+        /// Issue event-id (hex) or nevent (bech32)
+        #[arg(value_name = "ID|nevent")]
+        id: String,
+        /// Markdown body for the cover note
+        #[arg(long)]
+        body: String,
+        /// Use local cache only, skip network fetch
+        #[arg(long)]
+        offline: bool,
+    },
 }
 
 #[derive(Subcommand)]