fix: update Nix flake version and vendorHash

- Update version from 0.9.9 to 0.24.4 (current release)
- Regenerate vendorHash after dependency updates

Fixes bd-870

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

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

default.nix

@@ -1,7 +1,7 @@
 { pkgs, self }:
 pkgs.buildGoModule {
   pname = "beads";
-  version = "0.9.9";
+  version = "0.24.4";
 
   src = self;
 
@@ -9,7 +9,7 @@ pkgs.buildGoModule {
   subPackages = [ "cmd/bd" ];
   doCheck = false;
   # Go module dependencies hash (computed via nix build)
-  vendorHash = "sha256-oXPlcLVLoB3odBZzvS5FN8uL2Z9h8UMIbBKs/vZq03I=";
+  vendorHash = "sha256-5p4bHTBB6X30FosIn6rkMDJoap8tOvB7bLmVKsy09D8=";
 
   # Git is required for tests
   nativeBuildInputs = [ pkgs.git ];