feat: thread AhbContext through format_constraint_evaluation

[hf-kklein]

Summary

• PR 4 of the inject removal migration series
• Adds an optional ahb_context: AhbContext parameter to format_constraint_evaluation() and _build_evaluated_format_constraint_nodes()
• When ahb_context is provided, uses ahb_context.fc_evaluator and ahb_context.evaluatable_data directly, bypassing both @inject.params and inject.instance(TokenLogicProvider)
• When ahb_context is None, falls back to the existing inject-based path (full backward compatibility)
• Passes evaluatable_data explicitly as a keyword argument to bypass the @inject.params decorator (same pattern as PR 2 / feat: thread AhbContext through ConditionNodeBuilder (dual-path) #744)

Test plan

• All 533 existing tests pass
• pylint clean (10/10)
• isort + black formatting verified

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