PixelRefine: profile multiplier as --profile-multiplier flag; outlier rejection default off

(1) Promote the Term-2 profile-width multiplier from the PR_RMULT env knob to a real
BraggIntegrationSettings::profile_multiplier (default 6) + jfjoch_process
--profile-multiplier flag. Removes the last PR_* env knob; IndexAndRefine reads the
setting. (2) Flip the merge outlier rejection default to OFF (ScalingSettings
outlier_reject_nsigma 6 -> 0); it stays available via --reject-outliers <nsigma>, since
it helps the jet R-free but is dataset-dependent (drops crystal-2 CCref).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

common/BraggIntegrationSettings.cpp

@@ -72,6 +72,17 @@ float BraggIntegrationSettings::GetR1() const {
     return r_1;
 }
 
+float BraggIntegrationSettings::GetProfileMultiplier() const {
+    return profile_multiplier;
+}
+
+BraggIntegrationSettings &BraggIntegrationSettings::ProfileMultiplier(float input) {
+    if (input <= 0.0f)
+        throw JFJochException(JFJochExceptionCategory::InputParameterInvalid, "Profile multiplier must be positive");
+    profile_multiplier = input;
+    return *this;
+}
+
 float BraggIntegrationSettings::GetR2() const {
     return r_2;
 }