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>

packages/beads/default.nix

@@ -1,7 +1,6 @@
 # Beads package - issue tracker for AI-supervised coding workflows
 # Takes src as argument so it can be called from both overlay and flake packages
 { lib
-, stdenv
 , buildGoModule
 , fetchurl
 , go_1_25
@@ -13,7 +12,7 @@
 }:
 
 let
-  # nixpkgs ships Go 1.25.5, but beads' dolt deps require Go >= 1.25.6
+  # beads' dolt deps require Go >= 1.25.6 (GOTOOLCHAIN=auto can't download in sandbox)
   go_1_25_6 = go_1_25.overrideAttrs (old: rec {
     version = "1.25.6";
     src = fetchurl {
@@ -28,8 +27,7 @@ buildGoModule_1_25_6 {
   inherit version src;
   subPackages = [ "cmd/bd" ];
   doCheck = false;
-  # Regenerated vendorHash for commit 6a51223b (dolt server mode, Go 1.25.6)
-  vendorHash = "sha256-9RMy0+ZBFg1BAl8Z0EuZK4XVm9QYVekS9i/1ErOIB/c=";
+  vendorHash = "sha256-M+JCxrKgUxCczYzMc2czLZ/JhdVulo7dH2YLTPrJVSc=";
   nativeBuildInputs = [ git pkg-config ];
   buildInputs = [ icu ];
   meta = with lib; {