chore: update beads 0.49.6→0.52.0 and gastown, make gastown a proper flake

- beads: update to 0.52.0 (16af00d7), refresh vendorHash
- gastown: update to 35157d02, remove flake=false now that upstream has flake.nix
- gastown: add inputs.nixpkgs.follows and inputs.beads.follows to deduplicate deps
- Clean up stale comments

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

flake.nix

@@ -52,7 +52,8 @@
 
     gastown = {
       url = "github:steveyegge/gastown";
-      flake = false;  # No flake.nix upstream yet
+      inputs.nixpkgs.follows = "nixpkgs-unstable";
+      inputs.beads.follows = "beads";
     };
 
     perles = {
@@ -266,7 +267,7 @@
         # Flake input packages (beads, gastown) - these get version from input rev
         "custom-beads" = pkgs.callPackage ./packages/beads {
           src = inputs.beads;
-          version = "0.49.6-${beadsRev}";
+          version = "0.52.0-${beadsRev}";
         };
         "custom-gastown" = pkgs.callPackage ./packages/gastown {
           src = inputs.gastown;