fix: remove the hard seam across the sky at the far scenery crest

[Attacktive]

The bug

A straight horizontal line ran across the whole sky, well above the water — on the beach scene it sat at SEA_HORIZON - 0.078 (the sailboat's mast top), i.e. exactly at sceneryFarCrestY.

Two bands both terminated hard on that one row:

• drawHorizonGlow ramped alpha 0 → 95 and then its rect just stopped at the crest, dropping back to 0 in a single pixel.
• drawInterPlaneHaze started at alpha 55 on that same line, with nothing above it.

The fix

• The glow fills past the crest — TileMode.CLAMP holds the end color and the silhouettes cover it — so the band never ends on a visible edge.
• The haze ramps in from above the crest (0 → 55 → 0) instead of appearing at full strength on it.

Both scene planes still read the same; only the discontinuity is gone.

Verification

Rendered BEACH/DUSK at 1680×1050 on an emulator via a throwaway instrumentation harness that logs the sharpest row-to-row luminance steps in a clean sky column, at main and with this change:

	y = 0.7724 (the seam)	remaining top steps
before	delta 18.0	0.845–0.851
after	absent	0.845–0.853 only

What's left is the shoreline/reflection ramp at SEA_HORIZON, a genuine edge spread over ~10 rows rather than a 1px step. compileDebugKotlin and the unit tests pass.

🤖 Generated with Claude Code

[codacy-production]

Up to standards ✅

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