ci(check): room on the runner for the workspace's test binaries

The first `check` run after P6 landed (`bcd1048b`) died linking the
store's and the package's test binaries: "No space left on device",
ld killed by SIGBUS. The store's test closure now carries the file
reader (hayro, zip, quick-xml, and through ledger-import the Typst
typesetter: plan Q-9, D-61 moves the reader out after S4.5), and the
runner's disk had no room left for it with full debug info and
incremental caches.

The job drops incremental compilation (a fresh runner gains nothing
from it), keeps line tables only (file:line in a panic's backtrace at
a fraction of the size), removes the image's unused toolchains before
the build, and prints the disk before and after so the next squeeze
is visible.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HS8WZziDnyxunC23MUxrLp

.github/workflows/check.yml

@@ -12,9 +12,25 @@ concurrency:
 jobs:
   check:
     runs-on: ubuntu-24.04
+    # The runner's disk is small (the first run after P6 landed died in
+    # the linker: "No space left on device", ld killed by SIGBUS). A fresh
+    # runner gains nothing from incremental caches, and line tables keep
+    # file:line in a panic's backtrace at a fraction of full debug info.
+    env:
+      CARGO_INCREMENTAL: "0"
+      CARGO_PROFILE_DEV_DEBUG: line-tables-only
+      CARGO_PROFILE_TEST_DEBUG: line-tables-only
     steps:
       - uses: actions/checkout@v4
+      - name: Room for the build (the image ships toolchains we never use)
+        run: |
+          sudo rm -rf /usr/share/dotnet /usr/local/lib/android /opt/ghc \
+                      /opt/hostedtoolcache/CodeQL /usr/local/.ghcup
+          df -h / | tail -1
       - uses: jdx/mise-action@v2
       - name: GUI build dependencies
         run: sudo apt-get update && sudo apt-get install -y libxkbcommon-dev libgtk-3-dev
       - run: just check
+      - name: What the build used
+        if: always()
+        run: df -h / | tail -1