Let haru open on Windows again, and say why when it cannot

[beingsuz]

Requested by beingsuz · project thread

Before: on Windows, haru from main (the v0.7.0 draft) does nothing when opened. No window and no error appear.

After: the window opens again. If haru ever cannot open it, or crashes, a message box says why and where the details were saved (%LOCALAPPDATA%\haru\haru.log). Re-running Release for the v0.7.0 draft now also moves the draft's tag target to the commit the new binaries were built from.

The cause was my change in #3. It restricted wgpu to DX12 on Windows, but eframe builds wgpu without its DX12 backend (cargo tree -e features -i wgpu-core --target x86_64-pc-windows-msvc lists only vulkan and gles). That left no backend at all, so creating the surface failed and run_native returned an error. main printed that error to stderr, which a windows_subsystem = "windows" build does not have.

How:

• Backend. The backend is wgpu's own choice again: Vulkan, then OpenGL, with WGPU_BACKEND still overriding it. That is what v0.6.5 used. The opaque window and vsync from Fix the Windows port, offer the beta at install, and install WebView2 for web wallpapers #3 stay.
• Startup errors. Every way main gives up now goes through a new failure module. It still prints to stderr, appends to haru.log in haru's data folder, and on Windows shows a message box through rfd, a Windows-only dependency. haru's unsafe_code = "forbid" stays, which rules out calling MessageBoxW directly.
• Crashes. A panic hook logs every panic. A panic that ends the event loop is caught around run_native and shown once the window is gone. Showing it from inside the hook would mean running a modal loop while winit unwinds.
• Release workflow. When the version's release already exists as a draft, the update path now passes --target "$GITHUB_SHA" to gh release edit. A draft has no tag until Publish, which makes the tag from the draft's target. Without this, publishing the rebuilt v0.7.0 would tag the pre-fix commit while shipping post-fix binaries. Published releases are untouched.

How it was tested

Run under Wine 9.0 on a virtual X display, with both builds cross-compiled with mingw (x86_64-pc-windows-gnu):

Build	Result
main	Exits with code 1 in about a second. The only output is WGPU error: Failed to create surface for any enabled backend: {} on stderr, which Windows discards. This reproduces the report.
This branch	The window opens and draws, showing the install-kirie prompt with the WebView2 and beta checkboxes.
This branch with WGPU_BACKEND=dx12 (forcing the old failure)	An error box says haru could not find a graphics driver it can draw with. The same text lands in haru.log.
This branch with a temporary panic! in app setup (not committed)	The panic comes out of winit and run_native and shows in a box as "haru crashed in thread main: panicked at …". It is also logged.

Also: cargo fmt --all --check, cargo clippy --workspace --all-targets -- -D warnings (Linux and x86_64-pc-windows-gnu) and cargo test --workspace are clean, with 172 tests. The release workflow parses as YAML. Its changed branch runs only on a real release run.

Not tested: a real Windows machine and the MSVC release build. Wine drew through OpenGL on a software renderer, so the Vulkan path a real GPU will take was not exercised. It is the same path v0.6.5 used.

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