feat(php): add PHPUnit support with compact output (65%+ token savings)

[Beninho]

Summary

• New rtk phpunit command with a state-machine output filter (65%+ token savings)
• Supports all PHPUnit invocation variants: phpunit, vendor/bin/phpunit, bin/phpunit (Symfony), php vendor/bin/phpunit, php bin/phpunit

Changes

File	Change
src/phpunit_cmd.rs	New module — state-machine filter, binary detection, tee integration
src/main.rs	Routing, doc comment, is_operational_command registration
src/discover/rules.rs	PATTERNS regex + RtkRule with 5 rewrite prefixes
src/discover/registry.rs	10 classify/rewrite tests for all variants
tests/fixtures/phpunit_raw.txt	Realistic fixture (PHPUnit 10, 110 tests, 1 failure)
scripts/test-all.sh	PHP section (conditional on phpunit/vendor/bin presence)
README.md	Quick-ref line + hook mapping table entry
CHANGELOG.md	[Unreleased] feature entry

Filter design

State machine: Header → Failures → Done

PHPUnit 10.5.0 ...          ← stripped (Header state)
Runtime: PHP 8.2.0          ← stripped
.F.......  100/100 (100%)   ← stripped
Time: 00:01:23, Memory: ... ← stripped
There was 1 failure:        ← triggers Failures state
1) UserTest::testEmail      ← captured
Failed asserting ...        ← captured (up to 2 detail lines)
/path/to/test:42            ← captured
FAILURES!                   ← triggers Done state
Tests: 110, Assertions: 340, Failures: 1.  ← parsed for summary

Output:

PHPUnit: 110 tests, 340 assertions, 1 failures
═══════════════════════════════════════
Failures:
1. 1) UserTest::testEmail
   Failed asserting that false is true.
   /path/to/test:42

Test plan

• cargo test --all — 1134 passed, 0 failed
• cargo fmt --all && cargo clippy --all-targets — clean for updated files. See src/rake_cmd.rs:18:31
• Token savings test asserts ≥65% on realistic fixture
• All 5 invocation variants tested for classify + rewrite
• Manual: rtk phpunit --help shows description
• Manual: hook rewrites phpunit tests/ → rtk phpunit tests/