[alex-leb]

Adds a Mailgun::Routes wrapper for the v3 Routes API, the rules that handle incoming email. Until now routes could only be managed through the raw client.

Methods

Method	Endpoint
list	GET /v3/routes
create	POST /v3/routes
get	GET /v3/routes/{id}
update	PUT /v3/routes/{id}
remove	DELETE /v3/routes/{id}
match	GET /v3/routes/match

• Same conventions as the other wrappers: list returns items, create/update return the response hash, remove returns a boolean, no aliases.
• Several actions can be passed as an Array; they are sent as repeated action fields.
• All methods require a v3 client and raise ParameterError when a route ID or match address is missing.
• Usage is documented in docs/Routes.md, linked from the README.

Testing

• The routes integration spec now goes through the wrapper and replays the existing routes cassette (create, list, get, update, delete), still matching on request body.
• A new routes_match spec, recorded against the live API, creates a route, matches an address to it and deletes it. It also holds the argument and API version checks.
• The new cassette is scrubbed like the existing ones (API key, auth header, test domain), and its X-Mailgun-Key-Id value is replaced with a placeholder.
• Full suite, run without credentials: 419 examples, 0 failures; line coverage 96.38%; RuboCop clean.