Add --id flag to bd list for filtering by specific issue IDs

- Add --id flag accepting comma-separated IDs
- Implements ID filtering at CLI, RPC, and storage layers
- Normalizes IDs (trim, dedupe, remove empty) like labels
- Guards against excessive ID lists (max 1000)
- Works with other filters (status, priority, etc.)

Closes bd-200

Amp-Thread-ID: https://ampcode.com/threads/T-377464f2-1e7f-46f9-b23e-1e3cfd611061
Co-authored-by: Amp <amp@ampcode.com>

internal/rpc/protocol.go

@@ -93,6 +93,7 @@ type ListArgs struct {
 	Label     string   `json:"label,omitempty"`      // Deprecated: use Labels
 	Labels    []string `json:"labels,omitempty"`     // AND semantics
 	LabelsAny []string `json:"labels_any,omitempty"` // OR semantics
+	IDs       []string `json:"ids,omitempty"`        // Filter by specific issue IDs
 	Limit     int      `json:"limit,omitempty"`
 }