♻️ Convert ArrayModel generator to Stencil template

[MadsBogeskov]

Problem

ArrayModel.toSwift() uses inline string interpolation for the file wrapper.

Solution

Extract file wrapper to ArrayModel.stencil, keep complex body logic in Swift.

Testing

All 70 tests pass including golden file tests.

Stack

#169 → #179 → #180 → #181 → #182 → this PR → …

IOS-433

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Note

Low Risk
Low risk refactor that moves ArrayModel Swift output generation from inline string building to a Stencil template; behavior should remain the same aside from potential formatting/template rendering differences.

Overview
Refactors ArrayModel.toSwift() to stop manually assembling Swift source strings and instead render output via a new ArrayModel.stencil template using a context dictionary.

Updates ModelDefinition to pass the shared templateRenderer into the array model path, aligning array generation with the existing template-based approach used by other model types.

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