clang-tidy: Initial commit

Added initial .clang-tidy configuration file with recommended C++ checks
aligned with the OpenBMC-approved checklist. This setup enforces modern
C++ best practices and helps catch common issues early in development.

Change-Id: I27db4ef97555d921998a5b71f96f2eb8c7d444c2
Signed-off-by: Jayanth Othayoth <ojayanth@gmail.com>
diff --git a/.clang-tidy b/.clang-tidy
new file mode 100644
index 0000000..c31ad57
--- /dev/null
+++ b/.clang-tidy
@@ -0,0 +1,18 @@
+Checks: '-*,
+    bugprone-unchecked-optional-access,
+    modernize-use-nullptr,
+    readability-function-cognitive-complexity,
+    readability-function-size
+    '
+
+CheckOptions:
+-   key: readability-function-cognitive-complexity.Threshold
+    value: 25
+-   key: readability-function-size.LineThreshold
+    value: 60
+-   key: readability-function-size.ParameterThreshold
+    value: 6
+
+HeaderFilterRegex: (?!^subprojects).*
+
+WarningsAsErrors: '*'