Inflection-0 Add .clang-format based on Apple WebKit style

[nciric]

Summary

Adds a root .clang-format configuration tailored to the formatting conventions of the Apple-donated codebase to establish a clear contribution policy.

This will make two things easier:

1. Incoming contributions can focus on logic not style
2. We can enable CI to auto-format all incoming code before merging

Rationale & Codebase Analysis

The configuration uses BasedOnStyle: WebKit (the canonical Apple C++ style preset in clang-format) with fine-tuned project settings based on an analysis of all 641 C/C++ files (59,203 lines) in the repository:

• Column Limit (140): Over 96.4% of existing lines across the codebase are under 140 characters, minimizing unwanted line reflows while keeping lines bounded.
• Indentation & Tabs: 0 tabs across 59k+ lines. Configured for 4-space indentation (IndentWidth: 4, UseTab: Never).
• Bracing Convention:
  • Function definitions: Opening { on newline (used by 74.2% of .cpp functions and 87.6% of .hpp functions in src/inflection/).
  • Control flow (if, for, while): Attached { on same line (AfterControlStatement: Never).
  • else / catch: Attached (} else {, } catch (...) {).
• Namespace Indentation: Set to None to prevent unneeded 4-space indentation across all namespace contents.
• Pointers/References: Left-aligned (Type* ptr, Type& ref), matching over 87% of pointer declarations in the codebase.
• Constructor Initializers: Comma-first style (BreakConstructorInitializers: BeforeComma).