fix(scan): stabilize scan --fix + better output + FSAA default - #325

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@src/Assimp/Importer.cpp`:
- Around line 88-103: The retry path currently ORs in additionalFlags
(lightFlags |= additionalFlags) which can re-enable the post-process bits that
caused the initial failure; change this to only merge a curated safe subset:
define a SAFE_FALLBACK_FLAGS mask containing only known-safe aiProcess_* bits
(e.g., aiProcess_Triangulate, aiProcess_ValidateDataStructure,
aiProcess_LimitBoneWeights, aiProcess_PopulateArmatureData,
aiProcess_GlobalScale and optionally aiProcess_ConvertToLeftHanded) and replace
the OR with lightFlags |= (additionalFlags & SAFE_FALLBACK_FLAGS) so
importer.ReadFile(path, lightFlags) uses only the permitted fallback flags
(referencing lightFlags, additionalFlags, SAFE_FALLBACK_FLAGS,
convertToLeftHanded, and importer.ReadFile).

In `@src/Assimp/MaterialProcessor.cpp`:
- Around line 64-67: ensure the code checks the result of
ensureFirstPass(existingMaterial) before calling applyRTSSNormalMap: capture the
return value from ensureFirstPass (or the pass pointer it returns) and only call
applyRTSSNormalMap(existingMaterial, normalTexPtr->getName()) when
ensureFirstPass indicates success; if ensureFirstPass fails, skip the RTSS
normal-map application (and optionally log or handle the failure) to avoid
dereferencing a missing pass.

In `@src/FBX/FBXExporter.cpp`:
- Around line 477-487: buildSkeletonOnly currently casts away const and calls
reset() on the caller's Ogre::Skeleton, mutating external state; instead
preserve the const contract by not modifying the input: set m_skeletonOnly and
m_hasSkeleton as before, but do not const_cast the incoming pointer — either
store it as a const pointer (e.g. keep a const Ogre::Skeleton* m_skeletonConst)
or make an internal copy/clone of the skeleton and call reset() on that copy,
then assign m_skeleton to the internal copy; update references to m_skeleton
accordingly (or add/use m_skeletonConst) so export logic uses the
non-mutating/internal copy while leaving the caller's skeleton unchanged.

In `@src/OgreWidget_test.cpp`:
- Around line 251-260: This test modifies global QSettings by removing
ViewportSettingsKeys::fsaaSamples() without restoring it; update
TEST_F(OgreWidgetTest, FsaaDefaultsToZeroWhenUnset) to save the original
presence and value of that key (using QSettings::contains and value), perform
the remove and assertions (including widget->rebuildRenderWindow()), then
restore the original state at the end of the test (re-set the key if it existed
or remove it if it did not) so QSettings state is isolated and order-independent
for other tests.

In `@src/ScanConfig.h`:
- Around line 54-57: The comment for redundantKeyframesPctThreshold in
ScanConfig.h is out of sync with the default value; update the comment to
accurately state that the check is enabled by default at 40% (or change the
default to 0 to keep it disabled). Locate the redundantKeyframesPctThreshold
declaration and either edit the comment to read that redundant-keyframe warnings
are enabled by default and trigger at >=40%, or set
redundantKeyframesPctThreshold to 0.0 if you prefer to keep the check disabled
by default; ensure the comment and the variable default stay consistent.

---

Outside diff comments:
In `@src/CLIPipeline.cpp`:
- Around line 1829-1837: The simplify branch unconditionally dereferences entity
(calling entity->getParentSceneNode() and refreshAvailableAnimationState())
which crashes for animation-only inputs; add the same guard used in
resample/decimate: check isAnimOnlyInput before touching entity — if
isAnimOnlyInput, avoid dereferencing entity (either call
MeshImporterExporter::exporter with a nullptr node if supported or route to the
existing animation-only export path), otherwise proceed to call
entity->refreshAvailableAnimationState() and node =
entity->getParentSceneNode(); ensure MeshImporterExporter::exporter is invoked
with the appropriate node value and keep the existing error reporting
(SentryReporter::captureMessage / err()) on non-zero result.

---

Nitpick comments:
In `@src/Assimp/MaterialProcessor.cpp`:
- Around line 59-67: Add Sentry breadcrumbs for the normal-map load/apply and
skip branches by calling SentryReporter::addBreadcrumb("file.import", ...) at
each significant point: when the normal map fails to load (the branch that logs
"Failed to load normal map" using normalFilename and materialName), when a
normalTexPtr exists and you are about to apply it (before the log "Applying RTSS
normal map" using normalFilename and materialName), and also mirror this for the
later branch around lines 73-76; place these calls near the existing
Ogre::LogManager::getSingleton().logMessage invocations, include concise
messages referencing the materialName and normalFilename, and do not change
behavior of ensureFirstPass(existingMaterial) or
applyRTSSNormalMap(existingMaterial, normalTexPtr->getName()).

In `@src/CLIPipeline.cpp`:
- Line 1316: The command-line parsing contains a duplicate branch that checks if
(arg == "--analyze") { analyzeMode = true; continue; } — keep the first
occurrence (the one at the top of the argument-parsing block) and remove the
second duplicate to avoid redundancy; search for the repeated check in the
argument parsing loop (look for the variable arg and analyzeMode in
CLIPipeline.cpp) and delete the later if-block so analyzeMode is only set once.

In `@src/FBX/FBXExporter_test.cpp`:
- Around line 2303-2342: The test currently only checks that bones and
animations exist after calling FBXExporter::exportSkeletonOnlyFBX(skel.get(),
outPath) and will not catch regressions that export mesh data or fail to capture
the skeleton bind pose; before calling exportSkeletonOnlyFBX, freeze the
skeleton's bind pose on the skel instance (use the appropriate Ogre Skeleton API
to save/apply the binding pose for the bones created with createBone and the
animation created with createAnimation) and after
parseFBX(outPath.toStdString()) assert that the parsed Objects block (found via
findTopLevel) contains no "Model" or "Geometry"/mesh-related entries and that
only bone/node and animation objects exist (tighten EXPECT_GE checks to exact
counts or explicit absence assertions) so the test fails if mesh data is
exported or the bind pose was not preserved.

In `@src/FBX/FBXExporter.cpp`:
- Around line 2119-2145: The exportSkeletonOnlyFBX function lacks a Sentry
breadcrumb; add SentryReporter::addBreadcrumb("file.export", ...) calls to
record this new user-visible export flow: one breadcrumb at function start
(include the filePath and tag it as "skeleton-only" and maybe "start") and
another on failure before each early return/error log (e.g., when !skeleton,
filePath.isEmpty(), out not open, and when builder.buildSkeletonOnly fails) so
failures can be correlated; use the function name exportSkeletonOnlyFBX and the
filePath in the breadcrumb messages to make them unique and actionable.