feat(enhance): discard, tests against a mock ComfyUI, docs (#192)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/enhance/config.rs

@@ -127,7 +127,7 @@ impl EnhanceConfig {
                 bail!("{key} must be greater than 0");
             }
         }
-        if !(self.warn_above_megapixels > 0.0) {
+        if self.warn_above_megapixels.is_nan() || self.warn_above_megapixels <= 0.0 {
             bail!("warn_above_megapixels must be greater than 0");
         }
         let mut seen = std::collections::HashSet::new();
@@ -148,7 +148,7 @@ impl EnhanceConfig {
             if t.label.trim().is_empty() {
                 bail!("template {:?} needs a label", t.name);
             }
-            if !(t.output_megapixels > 0.0) {
+            if t.output_megapixels.is_nan() || t.output_megapixels <= 0.0 {
                 bail!("template {:?}: output_megapixels must be > 0", t.name);
             }
         }