Android: preserve NestedScrollView fling nested-scroll lifecycle

[AmatoGiulio]

Summary:

ReactNestedScrollView is generated from ReactScrollView, but the generated class extends AndroidX NestedScrollView.

For ordinary non-paging flings, the generated override currently invokes the reflected OverScroller directly and calls postInvalidateOnAnimation(). That bypasses NestedScrollView.fling(), so AndroidX never starts its TYPE_NON_TOUCH nested-scroll lifecycle.

This change keeps ReactScrollView unchanged and adjusts only the generated nested variant:

• pagingEnabled continues to use the existing flingAndSnap() path;
• ordinary ReactNestedScrollView flings delegate to super.fling(correctedVelocityY);
• React Native still initiates/owns the fling and keeps its existing momentum-event handling;
• the generator validates that the copied scroller branch exists exactly once before replacing it, failing closed if the source shape changes.

The generated ReactNestedScrollView.kt is regenerated from the updated generator.

Changelog:

[ANDROID] [FIXED] - Preserve the AndroidX non-touch nested-scroll lifecycle during ordinary ReactNestedScrollView flings.

Test Plan:

Generator validation:

node generate-nested-scroll-view.js
node generate-nested-scroll-view.js --verify

PASS

The same transformation was also regenerated successfully from the current 0.87-stable source shape.

RN 0.87 Android runtime probe with useNestedScrollViewAndroid=true, comparing stock and patched source with identical native fling velocities:

case                      velocity      stock NT  patched NT   stock y   patched y
ordinary-low              2500          0         1            178.29    178.29
ordinary-high             8000          0         1            1345.14   1345.14
top-edge                  -6000         0         1            0.00      0.00
bottom-edge                6000         0         1            18357.7   18357.7
deceleration-normal        6000         0         1            816.00    816.00
deceleration-fast          6000         0         1            201.90    201.90
perf-tag                   5000         0         1            594.67    594.67
paging                     6000         0         0            842.29    842.29
snap-interval              6000         0         0            960.00    960.00
snap-offsets               6000         0         0            2400.00   2400.00
disableIntervalMomentum    6000         0         0            1440.00   1440.00
programmatic               -             0         0            720.00    720.00

For ordinary deterministic flings, stock and patched final distances were identical (0.00% delta) while the patched source opened the AndroidX non-touch nested-scroll lifecycle. decelerationRate preserved the same fast/normal ratio (0.2474 in both variants).

A physical touch-fling probe also changed from TOUCH/NON_TOUCH = 1/0 stock to 1/1 patched.

Paging/snap cases remained on flingAndSnap() with NON_TOUCH = 0 in both variants and identical endpoints. Interruption and deterministic reversal (+8000 → touch interrupt → -8000) also passed.

The paging/snap branch is intentionally unchanged.

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