Add fuzz testing - #2

This pull request introduces property-based fuzz testing to both the modals and slottable packages using the fast-check library. The main changes include adding fast-check as a dependency, updating lock and workspace files, and adding comprehensive property tests to ensure correctness and robustness of core APIs.

Testing improvements:

• packages/modals/src/store.property.test.ts: Adds property-based fuzz tests for the modal store, simulating arbitrary sequences of stack operations and validating consistency, error handling, and stack capacity enforcement.
• packages/slottable/src/use-slot.property.test.tsx: Adds property-based fuzz tests for the useSlot hook and Slot component, verifying prop precedence, slot name resolution, and default/override behavior under a wide range of input combinations.

Dependency updates:

• packages/modals/package.json, packages/slottable/package.json: Adds fast-check as a test dependency. [1] [2]
• pnpm-workspace.yaml, pnpm-lock.yaml: Updates workspace and lock files to include fast-check and its dependency pure-rand. [1] [2] [3] [4] [5] [6] [7] [8]

Summary by CodeRabbit

• Tests
  • Added comprehensive property-based coverage for store behavior, including updates, removals, subscriptions, snapshots, notifications, errors, server rendering, and capacity limits.
  • Added property-based coverage for slot behavior, including prop precedence, fallbacks, overrides, and isolation.
• Chores
  • Added the testing library required to support randomized test scenarios.