fix(attribution): correct third-party credit, and assert it stays correct

[StuartCameronCode]

Fixes #72.

The reported bug

zsmooth was credited to "Adrian Woracz" in the README, the About dialog and NOTICES.txt. That name does not exist — the author's handle is adworacz and his LICENSE says Austin Dworaczyk Wiltshire. The handle had been expanded into a plausible-sounding human name instead of being looked up, and he found it himself.

Why this touches so much

Rather than patch the one line, I re-derived every attribution from upstream LICENSE files and source headers. The same class of error was throughout:

Wrong licences

Component	Listed as	Actually
CTMF	GPL-2.0	GPL-3.0
DCTFilter	GPL-2.0	MIT
AWarpSharp2	GPL-2.0	ISC
RemoveGrain / Repair	GPL-2.0	WTFPL (+ MIT for Clense)
FFmpeg	LGPL-2.1+	GPL-3.0 — every bundled build is --enable-gpl --enable-version3

Invented year ranges — Copyright (c) 2012-2024 … appeared on components whose upstream asserts no such range, including two that assert no copyright at all (havsfunc is Unlicense; FluxSmooth's original author explicitly disclaimed copyright).

Credited something not shipped — ffms2, removed alongside BestSource.

Omitted ~15 plugins that are shipped — Retinex, bifrost, fluxsmooth, DeScratch, VIVTC, TCanny, TTempSmooth, AddGrain, FFT3DFilter, KNLMeansCL, MiscFilters, TemporalMedian, BM3D, zimg, Zstandard, plus the Agner Fog Vector Class Library that eight HolyWu plugins compile in.

mvsfunc has no licence upstream at all — no LICENSE file, no header, nothing in setup.py. It was listed as "Unlicense". It now says so plainly, with an offer to remove it on request.

What else changed

• Original authors named where a port obscured them: Kevin Stone behind DFTTest/TCanny/TTempSmooth/NNEDI3CL, Simon Perreault behind CTMF, Tom Barry behind AddGrain, Fizick behind FFT3DFilter/DeScratch/Deblock, SEt behind AWarpSharp2, Sergey Stolyarevsky behind CCD, Didée behind QTGMC's ancestor TempGaussMC_beta2, SAPikachu behind neo_f3kdb, Akarin behind akarin.
• Permissive licence texts reproduced in full — MIT, ISC, WTFPL, BSD-3-Clause, Boost, zlib and the Unlicense all require the notice be included with the distribution, and none of them were.
• In-app strings — the Windows exe's file properties gave CompanyName and LegalCopyright as literally "com.vapourbox"; both platforms claimed "All rights reserved" on a GPL-3 app.
• Pre-built binary sources in the README now also credit martin-riedl, BtbN, python-build-standalone and the Homebrew bottle, not just the three macOS ones.

Guard

app/test/attribution_test.dart (4 tests, runs in the push gate — no deps needed) keeps the three places in step:

• every plugin in deps-expected-plugins.json is credited in NOTICES.txt
• every About-dialog component appears in NOTICES.txt
• no removed component (ffms2, BestSource) lingers
• every Licence text: file referenced actually exists in licenses/

It caught two of my own inconsistencies while I was writing it. What it cannot catch is a name that is simply wrong, so CLAUDE.md records the rule: a handle is not a name, a repo owner is not the copyright holder, and every copyright line comes from upstream at the time of writing.

Note on scope

bifrost, fluxsmooth and Retinex arrive with deps 1.9.0 on feat/advanced-mode-and-filter-curation, not on main — they are credited here anyway, since both branches land before the next release. Nothing else here depends on that branch; the two touch no common files apart from README.md and CLAUDE.md, which merged cleanly in testing.

Verification

• flutter test test/attribution_test.dart — 4/4
• flutter analyze — no new issues
• Every copyright line traced to an upstream LICENSE or source header (gh api repos/<r> for the SPDX id, raw file fetch for the holder)