github: Add clang format check workflow.

.clang-format

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+# SPDX-License-Identifier: Apache-2.0
+#
+# Note: The list of ForEachMacros can be obtained using:
+#
+#    git grep -h '^#define [^[:space:]]*FOR_EACH[^[:space:]]*(' include/ \
+#    | sed "s,^#define \([^[:space:]]*FOR_EACH[^[:space:]]*\)(.*$,  - '\1'," \
+#    | sort | uniq
+#
+# References:
+#   - https://clang.llvm.org/docs/ClangFormatStyleOptions.html
+
+---
+BasedOnStyle: LLVM
+AlignConsecutiveMacros: AcrossComments
+AllowShortBlocksOnASingleLine: Never
+AllowShortCaseLabelsOnASingleLine: false
+AllowShortEnumsOnASingleLine: false
+AllowShortFunctionsOnASingleLine: None
+AllowShortIfStatementsOnASingleLine: false
+AllowShortLoopsOnASingleLine: false
+AttributeMacros:
+  - __aligned
+  - __deprecated
+  - __packed
+  - __printf_like
+  - __syscall
+  - __syscall_always_inline
+  - __subsystem
+BitFieldColonSpacing: After
+BreakBeforeBraces: Attach
+ColumnLimit: 100
+ConstructorInitializerIndentWidth: 4
+ContinuationIndentWidth: 4
+ForEachMacros:
+  - 'ARRAY_FOR_EACH'
+  - 'ARRAY_FOR_EACH_PTR'
+  - 'FOR_EACH'
+  - 'FOR_EACH_FIXED_ARG'
+  - 'FOR_EACH_IDX'
+  - 'FOR_EACH_IDX_FIXED_ARG'
+  - 'FOR_EACH_NONEMPTY_TERM'
+  - 'FOR_EACH_FIXED_ARG_NONEMPTY_TERM'
+  - 'RB_FOR_EACH'
+  - 'RB_FOR_EACH_CONTAINER'
+  - 'SYS_DLIST_FOR_EACH_CONTAINER'
+  - 'SYS_DLIST_FOR_EACH_CONTAINER_SAFE'
+  - 'SYS_DLIST_FOR_EACH_NODE'
+  - 'SYS_DLIST_FOR_EACH_NODE_SAFE'
+  - 'SYS_SEM_LOCK'
+  - 'SYS_SFLIST_FOR_EACH_CONTAINER'
+  - 'SYS_SFLIST_FOR_EACH_CONTAINER_SAFE'
+  - 'SYS_SFLIST_FOR_EACH_NODE'
+  - 'SYS_SFLIST_FOR_EACH_NODE_SAFE'
+  - 'SYS_SLIST_FOR_EACH_CONTAINER'
+  - 'SYS_SLIST_FOR_EACH_CONTAINER_SAFE'
+  - 'SYS_SLIST_FOR_EACH_NODE'
+  - 'SYS_SLIST_FOR_EACH_NODE_SAFE'
+  - '_WAIT_Q_FOR_EACH'
+  - 'Z_FOR_EACH'
+  - 'Z_FOR_EACH_ENGINE'
+  - 'Z_FOR_EACH_EXEC'
+  - 'Z_FOR_EACH_FIXED_ARG'
+  - 'Z_FOR_EACH_FIXED_ARG_EXEC'
+  - 'Z_FOR_EACH_IDX'
+  - 'Z_FOR_EACH_IDX_EXEC'
+  - 'Z_FOR_EACH_IDX_FIXED_ARG'
+  - 'Z_FOR_EACH_IDX_FIXED_ARG_EXEC'
+  - 'Z_GENLIST_FOR_EACH_CONTAINER'
+  - 'Z_GENLIST_FOR_EACH_CONTAINER_SAFE'
+  - 'Z_GENLIST_FOR_EACH_NODE'
+  - 'Z_GENLIST_FOR_EACH_NODE_SAFE'
+  - 'STRUCT_SECTION_FOREACH'
+  - 'STRUCT_SECTION_FOREACH_ALTERNATE'
+  - 'TYPE_SECTION_FOREACH'
+  - 'K_SPINLOCK'
+  - 'COAP_RESOURCE_FOREACH'
+  - 'COAP_SERVICE_FOREACH'
+  - 'COAP_SERVICE_FOREACH_RESOURCE'
+  - 'HTTP_RESOURCE_FOREACH'
+  - 'HTTP_SERVER_CONTENT_TYPE_FOREACH'
+  - 'HTTP_SERVICE_FOREACH'
+  - 'HTTP_SERVICE_FOREACH_RESOURCE'
+  - 'I3C_BUS_FOR_EACH_I3CDEV'
+  - 'I3C_BUS_FOR_EACH_I2CDEV'
+  - 'MIN_HEAP_FOREACH'
+IfMacros:
+  - 'CHECKIF'
+IncludeCategories:
+  - Regex: '^".*\.h"$'
+    Priority: 0
+  - Regex: '^<(assert|complex|ctype|errno|fenv|float|inttypes|limits|locale|math|setjmp|signal|stdarg|stdbool|stddef|stdint|stdio|stdlib|string|tgmath|time|wchar|wctype)\.h>$'
+    Priority: 1
+  - Regex: '^\<zephyr/.*\.h\>$'
+    Priority: 2
+  - Regex: '.*'
+    Priority: 3
+IndentCaseLabels: false
+IndentGotoLabels: false
+IndentWidth: 4
+InsertBraces: true
+InsertNewlineAtEOF: true
+SpaceBeforeInheritanceColon: False
+SpaceBeforeParens: ControlStatementsExceptControlMacros
+SortIncludes: Never
+UseTab: ForContinuationAndIndentation
+TabWidth: 4
+WhitespaceSensitiveMacros:
+  - COND_CODE_0
+  - COND_CODE_1
+  - IF_DISABLED
+  - IF_ENABLED
+  - LISTIFY
+  - STRINGIFY
+  - Z_STRINGIFY
+  - DT_FOREACH_PROP_ELEM_SEP

.github/workflows/format_check.yml

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+name: Format Check
+
+on:
+  push:
+    paths:
+      - '**/*.{c,cpp,cc,cxx,h,hpp}'
+  pull_request:
+    types: [opened, edited, reopened, synchronize]
+    paths:
+      - '**/*.{c,cpp,cc,cxx,h,hpp}'
+
+jobs:
+  format-check:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+        with:
+          submodules: false
+          persist-credentials: false
+
+      - name: Install clang-format
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y clang-format
+
+      - name: Get changed files
+        id: changed-files
+        uses: tj-actions/changed-files@v46
+        with:
+          files: |
+            cores/arduino/**/*.{c,cpp,cc,cxx,h,hpp}
+            !cores/arduino/api/**
+            loader/**/*.{c,cpp,cc,cxx,h,hpp}
+            !loader/llext_exports.c
+            libraries/**/*.{c,cpp,cc,cxx,h,hpp}
+
+      - name: Run clang-format check
+        if: steps.changed-files.outputs.any_changed == 'true'
+        run: |
+          exit_code=0
+
+          for file in ${{ steps.changed-files.outputs.all_changed_files }}; do
+            file_fmt="${file}.tmp"
+            clang-format ${file} > ${file_fmt}
+            diff -q -u ${file} ${file_fmt} >> /dev/null 2>&1 || {
+              echo "❌ Formatting issues found in: $file"
+              colordiff -u ${file} ${file_fmt} || true
+              exit_code=1
+            }
+          done
+
+          exit $exit_code