NixOS: flake leaves out build/; export starvation tests start warm

The flake's source skips dev.sh's build folder, which nixpkgs' CMake
hook took for its own. ProjectExportFailureTests crashed on NixOS
inside fontconfig: its limit held the process's first font lookup.
initTestCase now opens a panel and an alert first, as the app has
before any export. A new test holds the JPEG render's snapshot to a
move.

Co-Authored-By: Claude <noreply@anthropic.com>

TASKS.md

@@ -280,7 +280,10 @@ The panel of 4.6 shows and edits what the session holds so far. Each item adds i
 - [x] 11.4b Standalone OmaPhoto: the port moves to its own public repository, `ZacharyZhang-NY/OmaPhoto` (the user's decision, 2026-09-26), the app at the root, the kernels in `kernels/`, the icons in `packaging/icons/`; renamed where a user sees it (name, binary, app id, desktop entry, icon, packages, logging, build options), Compositor's project format kept; the README credits Compositor; one install script per family in `scripts/install/`; `release.yml` builds and publishes the packages on a tag. Version 1.0.0.
 - 11.4 and 11.4b round 1 (Fable 5.1, max): FAIL, six findings. The DEB names Ubuntu 24.04's `t64` Qt libraries, which no later Ubuntu publishes, yet the README promised "24.04 or later" and `ubuntu.sh` let 26.04 through to apt's refusal: the script now takes `UBUNTU_CODENAME=noble` alone and the README says so. AGENTS.md said `lib/compositor` for the bundled runtime (now `lib/omaphoto`). The PKGBUILD's comment said `linux/packaging/arch`. `nixos.sh` installed `main`, not the release the README named: it now resolves the newest release's tag from GitHub's redirect and installs the flake there. Nothing tied the tag to the version the files carry: the workflow's first job refuses a tag that names another (checked by hand against a matching tag, a wrong CMake, PKGBUILD and flake version). No test pinned `project`: `DistortTests::pointsPastTheHorizonDivideAsSwiftDoes` carries a box above a trapezoid's horizon (w from -2 to -1) through `carried` and `mapPath`; on Arch the body and both call sites mutated to `map.map` each fail it, on Qt 6.4 they are equivalent (6.4's `map` divides too).
 - 11.4 and 11.4b round 2: PASS, no findings.
-- [ ] 11.4c NixOS: the flake leaves out `dev.sh`'s `build/` (the package's own build folder collided with it); ProjectExportFailureTests crashes in the full NixOS run, never alone: find the cause.
+- [x] 11.4c NixOS: the flake leaves out `dev.sh`'s `build/` (the package's own build folder collided with it); ProjectExportFailureTests crashes in the full NixOS run, never alone: find the cause.
+- 11.4c work: the flake's source leaves out the top-level `build/` (`cleanSourceWith`); the NixOS run built the package with it. The crash reproduced every time under ctest and run directly in a kept container with the check's own build; gdb put it in fontconfig's `FcHashTableFind`, under `QMessageBox::setText` in `showError`, under the PNG export's failed snapshot: the alert opened while the 512 KB limit held, and it was the process's first font lookup, whose failed allocation fontconfig dereferences. The app had already handled the failure (it logged the export error). `main` now resolves the alert's fonts before the tests, as the app's window does before any export: five direct runs and ctest pass in the container; with the PNG or the JPEG snapshot's alert removed (`mutate.py`), the test still fails.
+- 11.4c round 1: FAIL, two findings. `thePanelOpensWithoutCopyingTheSnapshot` passed only on the heap its siblings left: alone on the dev image it failed 40 of 40 (it crashed 45 of 45 before the fix), since its limit also held the panel's first open. `initTestCase` now opens a panel and an alert once, the refusal flow, before any limit (the fonts line in `main` went); every test alone and the whole binary pass 40 of 40 on Ubuntu, Arch and NixOS. AGENTS.md put the first font lookup on NixOS alone; it is the first on every system. `mutate.py` then found the JPEG render's capture could copy the snapshot unseen (a gap since 10.3): `theJPEGRenderTakesTheSnapshotWithoutACopy` holds it to a move under a 2 MB limit, the pool thread held so the render waits; the four mutants (both snapshot alerts removed, both captures copied) each fail.
+- 11.4c round 2: PASS, no findings.
 - [ ] 11.4d Issue #5: the RPM demands Fedora 42's exact ONNX Runtime (`libonnxruntime.so.1(VERS_1.20.1)`), and ONNX Runtime stamps a new symbol version on every release, so any other Fedora or update refuses it; the Arch package breaks at run time the same way. Packages carry the runtime they were built with, as the DEB does, and the RPM builds on the oldest Fedora still supported.
 - [ ] 11.4e Issues #1 and #2: `dev.sh run` reaches the host's files (the home folder) and the GPU's render nodes, and builds before it runs.
 - [ ] 11.4f Release 1.0.1: the fixes above, the Node 24 actions, the install scripts rerun against the new release; the issues answered and closed.