Remove bitflags dependency and replace with custom implementation

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[Copilot]

Pull Request Overview

This PR removes the external bitflags dependency and replaces it with a custom implementation to reduce external dependencies. The changes maintain the same API surface while implementing bitwise operations directly.

• Remove bitflags crate dependency from Cargo.toml
• Replace bitflags macro usage with custom Flags struct implementation
• Update clippy lint from allow to expect for better future compatibility

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/node.rs	Implements custom Flags struct with bitwise operations to replace bitflags macro
src/lib.rs	Removes bitflags extern crate declaration and updates clippy lint directive
Cargo.toml	Removes bitflags dependency from dependencies section

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