Meta: Revert to a stable rust compiler

Let's not depend on a nightly pre-release, especially not just for a
linting option. We can enable the linter option once it lands in the
stable release.

.github/actions/setup/action.yml

@@ -114,16 +114,6 @@ runs:
       if: ${{ inputs.os == 'macOS' || inputs.os == 'Android' }}
       uses: dtolnay/rust-toolchain@stable
 
-      # Avoid 'rustup toolchain install nightly'. When a newer nightly is published, it triggers an in-place toolchain
-      # update whose component swap renames files from /opt/rustup/toolchains/ to /opt/rustup/tmp/. And those land on
-      # different overlayfs mounts inside the runner container — producing "Invalid cross-device link (os error 18)".
-      # TODO: Remove once 'imports_granularity' rustfmt option is stable:
-      #       https://rust-lang.github.io/rustfmt/?version=v1.9.0&search=group#imports_granularity
-    - name: 'Ensure rustfmt is available on the nightly toolchain'
-      if: ${{ inputs.type == 'lint' }}
-      shell: bash
-      run: rustup component add rustfmt --toolchain nightly
-
     - name: 'Install wasm-tools'
       if: ${{ inputs.type == 'build' }}
       shell: bash

Meta/Docker/ci/VERSION

@@ -1 +1 @@
-2026.05.25
+2026.06.02

Meta/lint-ci.sh

@@ -48,10 +48,10 @@ else
     ((FAILURES+=1))
 fi
 
-if cargo +nightly fmt --check ; then
+if cargo fmt --check ; then
-    echo -e "[${GREEN}OK${NC}]: cargo +nightly fmt --check"
+    echo -e "[${GREEN}OK${NC}]: cargo fmt --check"
 else
-    echo -e "[${BOLD_RED}FAIL${NC}]: cargo +nightly fmt --check"
+    echo -e "[${BOLD_RED}FAIL${NC}]: cargo fmt --check"
     ((FAILURES+=1))
 fi
 

rust-toolchain.toml

@@ -1,4 +1,3 @@
 [toolchain]
-# TODO: Pin to a stable version once `imports_granularity` rustfmt option is stable. https://rust-lang.github.io/rustfmt/?version=v1.9.0&search=group#imports_granularity
+channel = "1.96.0"
-channel = "nightly"
 components = ["rustfmt", "clippy"]

rustfmt.toml

@@ -3,4 +3,6 @@ hard_tabs = false
 tab_spaces = 4
 edition = "2024"
 style_edition = "2024"
-imports_granularity = "Item"
+
+# FIXME: Enable this setting once it lands in a stable version.
+# imports_granularity = "Item"