ci: add cpplint action

.github/workflows/cpplint.yml

@@ -0,0 +1,8 @@
+name: cpplint
+on: [push, pull_request]
+jobs:
+  cpplint:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v6
+    - run: pipx run cpplint --recursive .

CPPLINT.cfg

@@ -1,3 +1,28 @@
 set noparent
+exclude_files=external/*
 filter=-build/header_guard,-build/include_subdir,-runtime/references,-readability/casting,-runtime/int,-build/include,-build/c++11,-build/c++14
+filter=-build/c++17
+filter=-build/namespaces
 filter=-legal/copyright
+filter=-readability/braces
+filter=-readability/multiline_comment
+filter=-readability/namespace
+filter=-readability/todo
+filter=-readability/utf8
+filter=-runtime/arrays
+filter=-runtime/casting
+filter=-runtime/explicit
+filter=-runtime/indentation_namespace
+filter=-runtime/string
+filter=-runtime/threadsafe_fn
+filter=-whitespace/blank_line
+filter=-whitespace/braces
+filter=-whitespace/comments
+filter=-whitespace/empty_if_body
+filter=-whitespace/end_of_line
+filter=-whitespace/ending_newline
+filter=-whitespace/indent
+filter=-whitespace/indent_namespace
+filter=-whitespace/line_length
+filter=-whitespace/parens
+filter=-whitespace/semicolon