fix(runtime): store active task's Waker in Scheduler

[Paraworker]

Fixed the issue where a future could be dropped on another thread, and ensured that futures are always dropped within the runtime context, because dropping a future may require access to the context.

Inspired by the implementation of async-executor::LocalExecutor.

Supersedes #493

[Copilot]

Pull Request Overview

This PR fixes an issue where futures could be dropped on the wrong thread by storing active task Wakers in the Scheduler and ensuring all futures are dropped within the runtime context. The implementation is inspired by async-executor::LocalExecutor.

Key changes:

• Added active_tasks field to Scheduler to track all active task wakers
• Introduced DropHook wrapper to execute cleanup when futures are dropped
• Implemented clear() method to properly clean up all tasks before scheduler destruction

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
compio-runtime/tests/drop.rs	Added test case to verify futures are properly dropped within runtime context
compio-runtime/src/runtime/scheduler/mod.rs	Added waker storage and clear mechanism to ensure thread-safe task cleanup
compio-runtime/src/runtime/scheduler/drop_hook.rs	New utility to run cleanup hooks when futures are dropped
compio-runtime/src/runtime/mod.rs	Implemented Drop for Runtime to clear scheduler tasks on destruction
compio-runtime/Cargo.toml	Made slab a required dependency and added pin-project-lite

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[George-Miao]

LGTM