Sell PRO as an in-app unlock, take shared photos, and let FX run negative

- One free Play app (com.locphamtran.recipescamera) with an expo-iap PRO
  unlock, replacing the paid apk for the store channel
- Android SEND/SEND_MULTIPLE share target feeds photos into the editor,
  on cold start and on resume
- BACK button in the TopBar and press-and-hold PEEK replace the chip row
- NOISE REDUCTION and SHARPENING accept -10: a negative SHARPENING softens
  the frame before the grain pass, a negative NOISE REDUCTION re-grains it,
  in the Skia engine, the live preview and the Kotlin export path alike

src/utils/exportEngine.ts

@@ -335,6 +335,24 @@ export async function processAndExportPhoto(
       }
     }
 
+    // Negative SHARPENING is the amount of digital edge enhancement to take
+    // back OUT. It runs HERE, inside the photo's own filter chain, because the
+    // post-grain twin (step 9) blurred the grain overlay away: NR < 0 plus
+    // SHARPENING < 0 exported as flat mush with no grain at all.
+    const sharpKnob = adjustments.sharpening ?? 0;
+    if (sharpKnob < 0) {
+      const softenSigma = (Math.abs(sharpKnob) / 10) * 3;
+      const softenFilter = Skia.ImageFilter.MakeBlur(
+        softenSigma,
+        softenSigma,
+        TileMode.Clamp,
+        imageFilter
+      );
+      if (softenFilter) {
+        imageFilter = softenFilter;
+      }
+    }
+
     if (imageFilter) {
       paint.setImageFilter(imageFilter);
     }
@@ -423,8 +441,18 @@ export async function processAndExportPhoto(
 
 
     // 6. Add Monochrome Grain Overlay
-    if (adjustments.grain > 0) {
-      const grainOpacity = adjustments.grain / 20; // up to 0.5 opacity
+    // NOISE REDUCTION below 0 works the other way round: it hands back the grain
+    // the denoiser would have flattened (a JPEG cannot be un-smoothed, but it
+    // can be re-grained). Same overlay as GRAIN, capped at the GRAIN slider's
+    // own ceiling so a negative NR plus GRAIN never double up.
+    // ponytail: re-grain, not de-noise; add a real grain-preserving NR the day
+    // the pipeline gets a pre-ISP raw frame.
+    const grainAmount = Math.min(
+      10,
+      Math.max(0, adjustments.grain) + Math.max(0, -(adjustments.denoise ?? 0))
+    );
+    if (grainAmount > 0) {
+      const grainOpacity = grainAmount / 20; // up to 0.5 opacity
       const grainPaint = Skia.Paint();
       grainPaint.setBlendMode(BlendMode.Overlay);
       grainPaint.setAlphaf(grainOpacity);
@@ -732,8 +760,10 @@ export async function processAndExportPhoto(
     let resultImage = outputSurface.makeImageSnapshot();
     // Sharpening knob (0..10) overrides the legacy boolean sharpen flag:
     // legacy camera captures keep sharpen:true → 0.5 fallback when knob is 0.
-    const sharpKnob = adjustments.sharpening ?? 0;
-    const sharpenAmount = sharpKnob > 0 ? (sharpKnob / 10) * 0.8 : options?.sharpen ? 0.5 : 0;
+    // A negative knob means "no sharpening at all" (its blur already ran at
+    // step 4, under the grain), so the legacy 0.5 fallback must not fire.
+    const sharpenAmount =
+      sharpKnob > 0 ? (sharpKnob / 10) * 0.8 : sharpKnob < 0 ? 0 : options?.sharpen ? 0.5 : 0;
     if (sharpenAmount > 0) {
       resultImage = screenSharpenImage(resultImage, sharpenAmount);
     }