feat: add graph links and hooks system (bd-kwro.2-5, bd-kwro.8)

- bd mail reply: reply to messages with thread linking via replies_to
- bd show --thread: display full conversation threads
- bd relate/unrelate: bidirectional relates_to links for knowledge graph
- bd duplicate --of: mark issues as duplicates with auto-close
- bd supersede --with: mark issues as superseded with auto-close
- Hooks system: on_create, on_update, on_close, on_message in .beads/hooks/
- RPC protocol: added Sender, Ephemeral, RepliesTo fields to CreateArgs/UpdateArgs

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

cmd/bd/create.go

@@ -10,6 +10,7 @@ import (
 	"github.com/spf13/cobra"
 	"github.com/steveyegge/beads/internal/config"
 	"github.com/steveyegge/beads/internal/debug"
+	"github.com/steveyegge/beads/internal/hooks"
 	"github.com/steveyegge/beads/internal/routing"
 	"github.com/steveyegge/beads/internal/rpc"
 	"github.com/steveyegge/beads/internal/types"
@@ -250,19 +251,22 @@ var createCmd = &cobra.Command{
 				FatalError("%v", err)
 			}
 
+			// Parse response to get issue for hook
+			var issue types.Issue
+			if err := json.Unmarshal(resp.Data, &issue); err != nil {
+				FatalError("parsing response: %v", err)
+			}
+
+			// Run create hook (bd-kwro.8)
+			if hookRunner != nil {
+				hookRunner.Run(hooks.EventCreate, &issue)
+			}
+
 			if jsonOutput {
 				fmt.Println(string(resp.Data))
 			} else if silent {
-				var issue types.Issue
-				if err := json.Unmarshal(resp.Data, &issue); err != nil {
-					FatalError("parsing response: %v", err)
-				}
 				fmt.Println(issue.ID)
 			} else {
-				var issue types.Issue
-				if err := json.Unmarshal(resp.Data, &issue); err != nil {
-					FatalError("parsing response: %v", err)
-				}
 				green := color.New(color.FgGreen).SprintFunc()
 				fmt.Printf("%s Created issue: %s\n", green("✓"), issue.ID)
 				fmt.Printf("  Title: %s\n", issue.Title)
@@ -393,6 +397,11 @@ var createCmd = &cobra.Command{
 		// Schedule auto-flush
 		markDirtyAndScheduleFlush()
 
+		// Run create hook (bd-kwro.8)
+		if hookRunner != nil {
+			hookRunner.Run(hooks.EventCreate, issue)
+		}
+
 		if jsonOutput {
 			outputJSON(issue)
 		} else if silent {