feat: Add RPC support for epic commands in daemon mode

- Added OpEpicStatus operation to protocol
- Implemented handleEpicStatus() in RPC server
- Added EpicStatus() method to RPC client
- Updated epic.go to use daemon RPC when available
- Server-side filtering for close-eligible reduces RPC payload
- Both 'bd epic status' and 'bd epic close-eligible' now work in daemon mode

Fixes #62
Closes bd-87

Amp-Thread-ID: https://ampcode.com/threads/T-44c6044e-de04-40a0-bac3-b26238c32a17
Co-authored-by: Amp <amp@ampcode.com>

internal/rpc/protocol.go

@@ -34,6 +34,7 @@ const (
 	OpCompactStats    = "compact_stats"
 	OpExport          = "export"
 	OpImport          = "import"
+	OpEpicStatus      = "epic_status"
 )
 
 // Request represents an RPC request from client to daemon
@@ -157,6 +158,11 @@ type CommentAddArgs struct {
 	Text   string `json:"text"`
 }
 
+// EpicStatusArgs represents arguments for the epic status operation
+type EpicStatusArgs struct {
+	EligibleOnly bool `json:"eligible_only,omitempty"`
+}
+
 // PingResponse is the response for a ping operation
 type PingResponse struct {
 	Message string `json:"message"`