feat: Add digital, dry, ink, and paint brush presets; implement regression testing hooks

- Introduced new crates for digital brushes, dry media brushes, ink brushes, and paint brushes, each containing various presets.
- Updated the menus to include "Paste Special" and "Paste as New Layer" options.
- Enhanced the feature scorecard tests to validate selection texture encoding.
- Added a regression gate workflow for automated testing on push and pull requests.
- Implemented Git hooks for pre-commit checks to ensure code formatting and run tests before commits.
- Created a settings file for local configurations.

scripts/install-git-hooks.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+set -Eeuo pipefail
+
+REPO_ROOT="$(git rev-parse --show-toplevel)"
+cd "$REPO_ROOT"
+
+git config --local core.hooksPath .githooks
+chmod +x .githooks/pre-commit .githooks/post-commit scripts/precommit-test-gate.sh
+
+configured="$(git config --local --get core.hooksPath)"
+if [[ "$configured" != ".githooks" ]]; then
+    echo "Failed to configure repository Git hooks." >&2
+    exit 1
+fi
+
+echo "Repository hooks installed: core.hooksPath=.githooks"