Refactor macdeploycheck installation and update Brewfile tap path

This commit modifies the `macdeploycheck` formula to install the script directly from the tapped repository instead of using a local file URL. Additionally, the `Brewfile` is updated to use the directory of the Brewfile for the tap path, ensuring compatibility when running `brew bundle` from different locations. The `install_brew_deps.sh` script is also enhanced to provide more detailed error messages when missing formulae are detected.

Brewfile

@@ -28,11 +28,10 @@ brew "gstreamer"
 
 # Strawberry requires KDAB's KDSingleApplication (CMake package name: KDSingleApplication-qt6).
 # Homebrew core doesn't consistently provide it, so this repo includes a local formula.
-# Homebrew requires formulae to be installed from a tap; `brew bundle` will tap *this repo*
-# using the current working directory (run `brew bundle` from the repo root).
-# If you previously tapped `strawberry/local` before `Formula/` existed, refresh it with:
-#   brew untap strawberry/local && brew tap strawberry/local "file://$PWD"
-tap "strawberry/local", "file://#{Dir.pwd}"
+# Homebrew requires formulae to be installed from a tap; we tap *this repo* via file://.
+# Use the Brewfile's directory (repo root) rather than the current working directory,
+# so `brew bundle --file /path/to/Brewfile` works no matter where you run it from.
+tap "strawberry/local", "file://#{File.expand_path(__dir__)}"
 brew "strawberry/local/kdsingleapplication-qt6"
 brew "strawberry/local/qtsparkle-qt6"      # optional: QtSparkle integration
 brew "strawberry/local/sparkle-framework" # optional: Sparkle integration (framework)