Refactor recognize to take params as kwarg

[cllns]

Fixes #271.

Router#recognize was silently ignoring the method: kwarg when called without an explicit params hash, returning the verb as GET for POST routes and often picking the wrong route.

Root cause: the old signature recognize(env, params = {}, options = {}) absorbed method: :post into the positional params argument, leaving options empty when it was handed to Rack::MockRequest.env_for.

Fixes the bug by moving to an explicit kwargs signature:

# Before
def recognize(env, params = {}, options = {})

# After
def recognize(target, params: {}, **options)

I also renamed env to target to reflect that the argument accepts a path, a route name, or a Rack env hash.

This is a breaking change, so will need to be for hanami-router v3. It seems like a good time to fix this "the right way" instead of making a backward-compatible fix that we'd have to continue to maintain. This new approach is much more explicit.

There's a slight behavior change in that we double splat the keyword args, so they're converted to symbols, so e.g. "HTTP_AUTHORIZATION" will get converted to a symbol, which Rack drops. There's a very simple fix though: callers who need this can build the env explicitly via Rack::MockRequest.env_for and pass it in as the target.

I worked with Claude Code to get this fixed, refactored, and all of the documentation updated.