fix: rename core modules to dt_ prefix to resolve namespace collisions

[avernikoz]

This PR renames the internal modules math, order, and pool to dt_math, dt_order, and dt_pool respectively.

Reasoning:
This is a workaround to bypass a known Sui Move compiler bug where automated address management (using 0x0 in Move.toml) causes namespace collisions when dependencies (like DeepBook) define modules with identical names.

References:

• Fixes namespace collisions with DeepBook's math, order, and pool modules.
• Bypasses Sui Issue #22194 (Namespace collision in dependencies).
• Bypasses Sui Issue #20112 (Namespace collision between packages' dependencies).

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Summary of Diff

The changes affect 34 files, primarily updating module declarations and their corresponding imports in both source files and test suites:

• math.move → dt_math
• order.move → dt_order
• pool.move → dt_pool
• Updated references in fee.move, fee_manager.move, helper.move, and all associated unit tests.