Blink parity: collapse blank lines between call/parameter arguments; gate to 0.4%

[TomasVotruba]

Collapses stray blank lines between function/call arguments. Measured drop: 21 to 15 differing files of 4527 (0.33%), 6 files fixed with zero regressions.

The issue

Pristine files had blank lines between arguments; ECS removes them, blink preserved them. Most visible with promoted constructor params carrying standalone attributes:

public function __construct(
    #[Autowire(env: 'json:...')]
    array $servers,
                          // blink kept a blank line here; ECS does not
    #[Autowire(env: 'string:...')]
    string $namespace,

Root cause and fix

Verified against real ECS (applied-checkers: MethodArgumentSpaceFixer): ECS collapses blank lines between call and declaration/parameter arguments (plain params, attributed promoted params, and plain call args), but preserves blank lines between array-literal items. blink's shared reflowParen preserved blanks in every context.

A collapseBlanks flag is threaded through reflowParen → reflowAfterComma → argNLAfterComma. Call/declaration/parameter callers collapse; array callers (ArrayListItemNewline, StandaloneLineInMultilineArray) preserve. This keeps the array-blank behavior that a prior change showed must be preserved.

Gate

MAX_DIFF_PERCENT lowered 0.5 to 0.4; actual is 0.33% (15 of 4527).

Fixed the 3 attribute-param files plus 3 more with the same blank-line issue (ConsoleErrorListener, EmailSubscriberTest, WebhookSubscriberTest). Unit tests cover attributed-param collapse, plain call-arg collapse, and array-item blank preservation. Full blink suite, go vet, golangci-lint green; strict rector-src 1:1 gate stays 0-diff.