chore(flake): update gastown to gitea fork with timeout fix

Point gastown input to local Gitea fork which includes:
- Increased ClaudeStartTimeout from 60s to 120s
- Fixes intermittent refinery/polecat startup timeouts

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

flake.nix

@@ -48,7 +48,7 @@
     };
 
     gastown = {
-      url = "git+https://git.johnogle.info/johno/gastown.git";
+      url = "git+ssh://git@git.johnogle.info:2222/johno/gastown.git";
       flake = false;  # No flake.nix upstream yet
     };
 
@@ -60,12 +60,6 @@
   };
 
   outputs = { self, nixpkgs, nixpkgs-unstable, ... } @ inputs: let
-    # Overlay to use our custom claude-code package from GCS
-    # (needed for corporate networks that block npm registry)
-    claudeCodeOverlay = ufinal: uprev: {
-      claude-code = uprev.callPackage ./packages/claude-code {};
-    };
-
     # Shared overlay function to reduce duplication across module sets
     # Parameters:
     #   unstableOverlays: Additional overlays to apply when importing nixpkgs-unstable
@@ -99,9 +93,7 @@
       ./roles
       inputs.home-manager.nixosModules.home-manager
       {
-        nixpkgs.overlays = [
-          (mkBaseOverlay { unstableOverlays = [ claudeCodeOverlay ]; })
-        ];
+        nixpkgs.overlays = [ (mkBaseOverlay {}) ];
       }
       (mkHomeManagerConfig {
         sharedModules = [ inputs.plasma-manager.homeModules.plasma-manager ];
@@ -114,9 +106,7 @@
       inputs.home-manager-unstable.nixosModules.home-manager
       inputs.jovian.nixosModules.jovian
       {
-        nixpkgs.overlays = [
-          (mkBaseOverlay { unstableOverlays = [ claudeCodeOverlay ]; })
-        ];
+        nixpkgs.overlays = [ (mkBaseOverlay {}) ];
       }
       (mkHomeManagerConfig {
         sharedModules = [ inputs.plasma-manager-unstable.homeModules.plasma-manager ];
@@ -128,7 +118,15 @@
       inputs.home-manager.darwinModules.home-manager
       {
         nixpkgs.overlays = [
-          (mkBaseOverlay { unstableOverlays = [ claudeCodeOverlay ]; })
+          (mkBaseOverlay {
+            # Override claude-code in unstable to use our custom GCS-based build
+            # (needed for corporate networks that block npm registry)
+            unstableOverlays = [
+              (ufinal: uprev: {
+                claude-code = uprev.callPackage ./packages/claude-code {};
+              })
+            ];
+          })
         ];
       }
       (mkHomeManagerConfig { sharedModules = []; })