add clang-format configuration

This will ensure our coding style is more clearly defined and allow
contibutors to auto-format their code, bringing some more consistency.

.clang-format

@@ -0,0 +1,48 @@
+BasedOnStyle: LLVM
+
+ColumnLimit: 100
+
+IndentWidth: 4
+IndentGotoLabels: false
+
+AlignArrayOfStructures: Left
+AlignConsecutiveAssignments: None
+AlignConsecutiveMacros: AcrossEmptyLines
+AlignConsecutiveDeclarations:
+  Enabled: true
+  # Available only with clang-format 20+
+  # AlignFunctionDeclarations: true
+  AlignFunctionPointers: true
+
+# Ensure we either have all args/params on a single line,
+# or only one per line
+BinPackArguments: false
+BinPackParameters: false
+# To be changed for clang-format 20+
+# BinPackParameters: OnePerLine
+
+# Avoid single-line enums/functions/ifs/loops/etc
+AllowShortBlocksOnASingleLine: Never
+AllowShortEnumsOnASingleLine: false
+AllowShortFunctionsOnASingleLine: None
+AllowShortCaseExpressionOnASingleLine: false
+AllowShortCaseLabelsOnASingleLine: false
+AllowShortIfStatementsOnASingleLine: Never
+AllowShortLoopsOnASingleLine: false
+
+BreakBeforeBinaryOperators: None
+# Ensure function opening brackets are on their own line
+BreakBeforeBraces: Linux
+# Available only with clang-format 20+
+# BreakBinaryOperations: OnePerLine
+
+InsertNewlineAtEOF: true
+
+# Don't be too strict on line lengths
+PenaltyExcessCharacter: 10
+# Prefer breaking arguments list over putting a function call
+# on its own line after an assignment
+PenaltyBreakAssignment: 200
+PenaltyBreakBeforeFirstCallParameter: 200
+# Ensure we never ever have the return type on a single line
+PenaltyReturnTypeOnItsOwnLine: 1000