fix(release): give rustc 1.99 enough stack; Windows build fails fast

rustc 1.99 overflows its default 8 MB stack compiling the crate in
release on Windows and macOS. Raise RUST_MIN_STACK to 64 MB in the cargo
config and the release workflow (the latter also covers rebuilding older
commits). The Windows Build step now runs in bash so a failed cargo build
stops the job instead of surfacing later as a missing exe at signing.
workflow_dispatch gains tag/commit inputs to rebuild a published release.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.cargo/config.toml

@@ -30,6 +30,8 @@ rustflags = [
     "-Clink-arg=/STACK:16777216",
 ]
 
+# Also sizes rustc's own threads: rustc 1.99 overflows the default 8 MB
+# compiling this crate in release on Windows/macOS.
 [env]
-RUST_MIN_STACK = "8388608"
+RUST_MIN_STACK = "67108864"
 

.github/workflows/release.yml

@@ -24,9 +24,21 @@ on:
         options:
           - all
           - snap
+      # Rebuild an already-published release: tag plus the commit it points at.
+      tag:
+        description: Existing release tag to rebuild (optional)
+        default: ''
+        type: string
+      commit:
+        description: Commit the tag points at (required with tag)
+        default: ''
+        type: string
 
 env:
   RELEASE_TAG: ${{ inputs.tag || github.event.release.tag_name }}
+  # Mirrors .cargo/config.toml so rebuilding a commit that predates the bump
+  # still gives rustc 1.99 enough stack.
+  RUST_MIN_STACK: "67108864"
 
 jobs:
   build-appimage:
@@ -238,6 +250,7 @@ jobs:
       - name: Build
         env:
           OCS_PATREON_TOKEN: ${{ secrets.OCS_PATREON_TOKEN }}
+        shell: bash
         run: |
           cargo build --locked --release
           cargo build --locked --release -p dwg-thumbnailer-win