feat(editor): UVDoc dewarp in editor + edge-support corner ranking v1.088 User report: curled documents keep their curve in the result, and auto corners often land wrong. CamScanner APK analysis confirmed they crop to a curved border then run an MNN dewarp net; we already ship UVDoc (same class of tool) but only used it in the batch ScanPipeline, never in the manual editor path. - EditorActivity.onNext is now async (lifecycleScope + Dispatchers.Default with a busy overlay). New EditorFlatten.run does hi-res perspective warp -> UVDoc curve/crease dewarp (edgeInset 0, falls back to the perspective result on failure) -> sharpen. This is the core "creases not flattened" fix. Validated in the python spike: the reported curled form flattens cleanly (right-side table straightened, Hough horizontal-line spread 1.79 -> 1.38). - EdgeSupport (new) scores how well a candidate quad sits on real paper edges (per-edge normal-scan gradient support ratio). CornerCandidates now ranks candidates best-first by this score (stable sort keeps AI first on ties). Validated: truncated / inner-table-border / over-extended quads all score below the true boundary. - Corner-snap dimensions are snapshotted before the background dispatch and editor tools are disabled while busy, so rotating mid-process cannot desync the warp scale. - Extracted EditorFlatten + EditorFilters to keep EditorActivity at 300 lines. Constraint: EditorFlatten owns hi-res bitmap recycling; UVDoc/sharpen each return a new bitmap and recycle their input only when it differs. Confidence: high Scope-risk: module Reversibility: moderate Directive: 8-point curved crop and CamScanner-style filter parity are the next iterations. Tested: assembleDebug + testDebugUnitTest exit=0 (26 tests, EdgeSupportTest 4 new); python UVDoc + edge-support simulations; reviewer agent pass after addressing file-size and rotate-race findings. Not-tested: on-device end-to-end with the reported document. Related: docs/ENGINEERING_LOG.md section 2 (dewarp), CamScanner libpagescanner analysis 🐙 Autopus