remove redundant array allocation in HandlebarsCompiler.Compile

[SimonCropp]

No description provided.

[rexm]

Looks like this change causes some unit test failures

[rexm]

CI failure diagnosis

The benchmark and test failures are caused by removing .ToArray() in this PR.

Tokenizer.Tokenize(source) returns a lazy IEnumerable backed by a forward-only TextReader. The old .ToArray() eagerly materialised all tokens before any converter touched them. Without it, BlockAccumulator.ConvertTokens consumes the enumerator while building block expressions, and a downstream LINQ operation then gets an already-exhausted iterator — causing System.InvalidOperationException: Sequence contains no elements in the benchmark and test runs.

The .ToArray() is load-bearing: the token stream is a single-pass reader that cannot be re-enumerated. Removing it is not safe here.

Fix: restore the .ToArray() call, or materialise the sequence at the point where it's first passed into the converter pipeline.

[rexm]

Claude recommended the "fix" but I think this PR is just not valid. We do need the array allocation here.