v1.3: Auto makeup gain, spectrum analyzer, FIR normalization, README overhaul

- Auto makeup gain: RMS-based loudness compensation from actual FIR response
- Real-time FFT spectrum analyzer behind EQ curves
- FIR normalization fix: flat settings now produce exact 0 dB passthrough
- Brickwall limiter (0 dB ceiling) with toggle
- Drag-and-drop signal chain reordering
- Low FIR tap count warning for 512/1024
- Double-click reset on all knobs
- Comprehensive README with linear phase EQ explanation

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Source/PluginEditor.h

@@ -44,7 +44,7 @@ private:
     NodeParameterPanel nodePanel;
 
     juce::Label titleLabel { {}, "INSTALPEQ" };
-    juce::Label versionLabel { {}, "v1.2.2" };
+    juce::Label versionLabel { {}, "v1.3.0" };
     juce::ToggleButton bypassToggle;
     juce::Label bypassLabel { {}, "BYPASS" };
 
@@ -57,8 +57,9 @@ private:
     juce::Label masterGainLabel { {}, "MASTER" };
     juce::ToggleButton limiterToggle;
     juce::Label limiterLabel { {}, "LIMITER" };
-    juce::Slider makeupGainSlider;
-    juce::Label makeupGainLabel { {}, "MAKEUP" };
+    juce::ToggleButton autoMakeupToggle;
+    juce::Label autoMakeupLabel { {}, "AUTO GAIN" };
+    juce::Label autoMakeupValue { {}, "0.0 dB" };
 
     SignalChainPanel chainPanel;