Fix: axis permutations silently erased by transform simplification

[NicoKiaru]

Fixes #52

Summary

RealViewsSimplifyUtils.isExlusiveTranslation misclassified axis-permutation
matrices as pure translations. simplifyAffineGet then rebuilt them from the
translation column only, silently discarding the permutation: shapes stayed
intact and the translation was roughly right, but the orientation was lost.

Root cause

The classifier coupled the off-diagonal test to val != 1.0:

if ( val != 0.0 && ( ( r == c && val != 1.0 ) || ( c != n && val != 1.0 ) ) ) return false;

For an off-diagonal entry (r != c, c < n) equal to 1.0, neither clause
fires, so it is accepted. The diagonal rule ("must be 1") was wrongly applied to
every in-matrix entry, instead of "off-diagonal must be 0". A concrete Y/Z swap:

[ 1 0 0 | tx ]
[ 0 0 1 | ty ]   <- m12 = 1, off-diagonal, wrongly accepted
[ 0 1 0 | tz ]   <- m21 = 1, off-diagonal, wrongly accepted

passed as a pure translation. A tiny rotation (e.g. 0.5 deg) turns the exact
1.0 entries into 0.9999..., which trips val != 1.0 and accidentally masks
the bug -- explaining why a small "nudge" appeared to fix it.

Fix

Replace the conflated condition with the three explicit rules:

if ( c == n ) { continue; }                            // translation column: any value
if ( r == c ) { if ( val != 1.0 ) return false; }      // diagonal must be 1
else if ( val != 0.0 ) return false;                   // off-diagonal must be 0

Permutations now fail classification and fall through to the lossless generic
affine copy. No information is dropped.

Scope

The sibling classifiers (isExclusiveScale, isExclusiveScaleAndTranslation)
were reviewed and are not affected: both already disqualify any non-zero
off-diagonal entry regardless of value. boundingInterval/estimateBounds use
the full matrix and handle off-diagonal terms correctly. This was the only
erasure path.

The public method name isExlusiveTranslation (sic) is kept unchanged to avoid
breaking API compatibility.

Tests

Added to RealViewsSimplificationsTest (committed first, red before the fix):

• isExlusiveTranslation must reject PERMUTATION2D / PERMUTATION3D
• simplifying a permutation must not yield a Translation*
• simplifying a permutation must preserve the full matrix

Full module test suite passes after the fix.

[bogovicj]

Good catch. This looks good

[bogovicj]

Thanks @NicoKiaru !