Add beads and gastown to CI cache, consolidate CI workflow

- Add packages/beads and packages/gastown with shared definitions
- Expose custom-beads and custom-gastown in flake packages output
- Consolidate CI from matrix (8 parallel jobs) to single job with loop
- Saves ~12 minutes of redundant nix-setup time per run
- Uses ::group:: for collapsible log sections per package

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

flake.nix

@@ -234,7 +234,7 @@
       ];
     };
 
-    # Packages for CI caching (custom packages and qt-pinned)
+    # Packages for CI caching (custom packages, flake inputs, and qt-pinned)
     packages = nixpkgs.lib.genAttrs [ "x86_64-linux" "aarch64-linux" ] (system:
       let
         pkgs = import nixpkgs {
@@ -246,6 +246,9 @@
           inherit system;
           config.allowUnfree = true;
         };
+        # Version strings for flake input packages
+        beadsRev = builtins.substring 0 8 (inputs.beads.rev or "unknown");
+        gastownRev = builtins.substring 0 8 (inputs.gastown.rev or "unknown");
       in {
         "custom-claude-code" = pkgs.custom.claude-code;
         "custom-app-launcher-server" = pkgs.custom.app-launcher-server;
@@ -253,6 +256,15 @@
         "custom-tea-rbw" = pkgs.custom.tea-rbw;
         "custom-rclone-torbox-setup" = pkgs.custom.rclone-torbox-setup;
         "qt-pinned-jellyfin-media-player" = pkgsQt.jellyfin-media-player;
+        # Flake input packages (beads, gastown) - these get version from input rev
+        "custom-beads" = pkgs.callPackage ./packages/beads {
+          src = inputs.beads;
+          version = "0.49.6-${beadsRev}";
+        };
+        "custom-gastown" = pkgs.callPackage ./packages/gastown {
+          src = inputs.gastown;
+          version = "unstable-${gastownRev}";
+        };
       }
     );