feat(hoist): pre-compute loop hoisting metadata at compilation time

[anakrish]

Introduce a compiler pass that analyzes and pre-computes loop hoisting information during policy compilation. This hoisted metadata is stored in lookup tables and made available to downstream consumers:

• interpreter: use HoistedLoop entries during evaluation (replaces runtime scanning)
• type inference: can leverage pre-computed loop structure for type propagation
• RVM compiler: will consume hoisting metadata for optimized bytecode generation

Changes:

• populate loop hoisting tables during engine preparation and query snippet execution
• refactor eval_stmts_in_loop and eval_output_expr_in_loop to consume HoistedLoop directly
• add helper methods for accessing loop expressions, collections, and indices from HoistedLoop
• extend Lookup with get_checked and into_slots for safe query context access and merging

[Copilot]

Pull Request Overview

This PR introduces a compilation-time loop hoisting optimization that pre-computes loop metadata during policy preparation, storing it in lookup tables for efficient runtime evaluation. This replaces the previous runtime loop scanning approach with cached results that can be reused across multiple evaluations.

• Adds a new compiler module with loop hoisting and scope context functionality
• Refactors interpreter loop handling to consume pre-computed HoistedLoop structures
• Extends the Lookup utility with bounds checking and module management capabilities

Reviewed Changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/compiler/hoist.rs	Implements the main LoopHoister that pre-computes loop metadata for statements and expressions
src/compiler/context.rs	Defines ScopeContext for tracking variable bindings during compilation
src/interpreter.rs	Updates loop evaluation to use pre-computed HoistedLoop data instead of runtime analysis
src/engine.rs	Integrates loop hoisting into policy preparation and query snippet execution
src/lookup.rs	Adds safe bounds checking and module management methods
src/compiled_policy.rs	Stores the loop hoisting table in compiled policy data

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[Copilot]

The .or(None) is redundant here. Option::as_ref() already returns an Option, so this can be simplified to just loop_info.key.as_ref().

Suggested change

	loop_info.key.as_ref().or(None)
	loop_info.key.as_ref()

[dpokluda]