fix: windows compatibility

[metalurgical]

Description

General windows support across the workspace and contracts artifact handling. Refactoring for correct conditional dependency scoping and removing hacks around this.

Changes

• Unix-only allocator scoping across multiple binaries.
• Windows-safe database test config
• Cross-platform shutdown handling in e2e solver setup
• Observe crate made platform-aware
• Contracts build script now normalizes artifact inputs

How to test

Apply normal testing strategy, this should be unaffected.

Related Issues

General improvement, not related to a specific issue.

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[metalurgical]

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[metalurgical]

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