Refactor Router: compile cache, dead code removal, and standards cleanup

[Copilot]

Router had no caching for the expensive regex compilation step, dead unreachable guards, legacy list() syntax, and null coercions in string concatenation.

Performance

• Compile cache: compile() memoizes results in $this->cache[$route]; repeated calls for the same pattern return immediately
• clearRoutes() now resets $cache alongside $routes and $names
• strpos replaces stripos in method matching — both operands are already uppercased, case-insensitive variant was wasteful

Dead code

• Removed unreachable guard in addRoutes(): TypeCheck::isArray() is always true for a typed array parameter; instanceof \Traversable is never true on a plain PHP array

Coding standards

• list() → [] destructuring throughout (match(), generate(), compile())
• null → '' in compile() pattern concatenation — eliminates implicit type coercion
• $strpos → $queryPos — avoids shadowing the built-in strpos name
• foreach/unset loop for stripping numeric capture-group keys → Arrayify::filter(..., ARRAY_FILTER_USE_KEY)
• Inlined $routeMethodMatch boolean — replaced with a direct continue guard

// Before: recompiles regex on every call for same route
$regex = $this->compile($route); // no caching

// After: cache hit on repeated routes
protected function compile(string $route): string
{
    if ( isset($this->cache[$route]) ) {
        return $this->cache[$route];
    }
    // ... build $compiled ...
    return $this->cache[$route] = "`^{$compiled}$`u";
}

[Copilot]

Pull request overview

This PR refactors Router to improve performance and readability by caching compiled route regexes, removing unreachable/dead code paths, and modernizing syntax.

Changes:

• Add a compiled-regex memoization cache in compile() and reset it in clearRoutes().
• Simplify route method matching (use strpos after uppercasing, inline guard/continue).
• Modernize code style: list() → [] destructuring, remove null concatenations, and simplify param-key filtering.

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