Add experimental --turbo option running the reco Go binary

[TomasVotruba]

What

Adds an experimental --turbo flag to bin/ecs check. Instead of running the PHP engine, it hands the resolved paths to the reco Go binary - a PHP parser and rewriter written in Go.

vendor/bin/ecs check --turbo          # report only (dry run)
vendor/bin/ecs check --turbo --fix    # rewrite files in place
vendor/bin/ecs check src --turbo      # path before the flag

How

• ECS resolves the source paths from ecs.php (and any CLI paths) exactly as usual, then invokes reco over them.
• The check/fix split maps straight onto reco:
  • --turbo runs reco run --dry-run <paths> - reports without writing.
  • --turbo --fix runs reco run <paths> - rewrites in place.
• Binary resolution order: ECS_TURBO_BIN env var -> vendor/bin/reco -> reco on PATH.
• reco's exit code is mapped onto ECS exit codes (0 stays success, non-zero becomes CHANGED_CODE_OR_FOUND_ERRORS).
• symfony/process is in replace, so the shell-out uses passthru with escaped arguments.

Prototype caveat

This is an RFC-stage prototype. In turbo mode reco runs its own native rule set, not the sniffs and fixers configured in ecs.php - only the paths are shared, the rule selection is ignored for now. A turbo run is not yet equivalent to a normal ECS run. This is documented in docs/turbo.md.

Remaining delivery work

For --turbo to work out of the box the reco binary has to ship alongside ECS:

• ship reco as downloadable per-OS binaries via goreleaser releases;
• add a Composer post-install step that downloads the matching binary into vendor/bin/reco.

Until then, build reco and point ECS_TURBO_BIN at it, or put it on PATH.

Tests

New unit tests under tests/Turbo. composer lint (phpstan level 8 + rector + check-cs) and composer test pass locally.