[perf] "Force" inline in inverseNtt hot path (#291)

`@inline(__always)` helps optimized code-gen in the hot branch as observed in
profiler and benchmarks -> ~50% wall time or 2x speed up for `InverseNtt UInt32 metrics`.

Co-authored-by: Roberto Santos <ra_santos@apple.com>

Author: adlich

Sources/HomomorphicEncryption/PolyRq/PolyRq+Ntt.swift

@@ -1,4 +1,4 @@
-// Copyright 2024-2025 Apple Inc. and the Swift Homomorphic Encryption project authors
+// Copyright 2024-2026 Apple Inc. and the Swift Homomorphic Encryption project authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -405,7 +405,8 @@ extension _NttContext {
             let kTimesModulus = modulus &<< lazyReductionCounter
 
             if m == 1 {
-                // Final stage, folding in multiplication by n^{-1} and modular reduction
+                // swiftlint:disable:next local_doc_comment
+                /// Final stage, folding in multiplication by n^{-1} and modular reduction
                 func applyOp(_ op: (_ x: inout T, _ y: inout T) -> Void) {
                     for xIdx in 0..<nDiv2 {
                         let yIdx = xIdx &+ nDiv2
@@ -451,6 +452,7 @@ extension _NttContext {
                     applyOp { _, _ in }
                 }
             } else {
+                @inline(__always)
                 func applyOp(_ op: (_ x: inout T, _ y: inout T) -> Void) {
                     for i in 0..<m {
                         let inverseRootOfUnity = inverseRootOfUnityPowers[rootIdx &+ i]