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/client.go

@@ -307,3 +307,8 @@ func (c *Client) Export(args *ExportArgs) (*Response, error) {
 func (c *Client) Import(args *ImportArgs) (*Response, error) {
 	return c.Execute(OpImport, args)
 }
+
+// EpicStatus gets epic completion status via the daemon
+func (c *Client) EpicStatus(args *EpicStatusArgs) (*Response, error) {
+	return c.Execute(OpEpicStatus, args)
+}