feat: add xcodebuild test filter (TOML)

[FlorianBruniaux]

Context

rtk discover from a real iOS developer session shows xcodebuild test used 7 times with no savings. Output is notoriously verbose.

Problem

xcodebuild test output is extremely noisy — hundreds of lines of compilation logs, boilerplate headers, and verbose test runner output for what is usually a simple pass/fail result.

Typical raw output includes:

• Build phase headers (=== BUILD TARGET ...)
• Compilation lines (CompileC, CompileSwift, Ld, etc.)
• Simulator bootstrap messages
• Per-test verbose lines (Test Case '-[...]' started.)
• On failure: assertion details (valuable, must keep)

Proposed TOML filter

A xcodebuild-test.toml filter that:

• Strips compilation/build phase lines
• Strips simulator startup noise
• Shows only test results: passed, failed, error
• Keeps failure details (assertion messages, file:line)
• Shows summary line (Executed N tests, with N failures)

Match on ^xcodebuild\b.*test (or ^xcodebuild test).

Real-world example

xcodebuild test -scheme ShopmiumSandbo.. -destination 'platform=iOS Simulator,...'

Token savings estimate

~85-90% — similar to cargo test filter which achieves 90%+.

Priority

Medium — iOS/macOS devs using Claude Code is a growing segment. xcodebuild is their equivalent of cargo test.