feat(hono): add useLogger() middleware for route-scoped logger injection

[gambonny]

This PR introduces a new Hono integration middleware useLogger() to simplify logger setup across routes using cflo.

• Injects getLogger(route) into c.var, scoped to each request
• Automatically enriches meta.route for all log calls
• Does not override core logger behavior (info, debug, etc.)
• Fully typed via DotSeparated
• Optimized for ergonomics and consistency with Hono middleware conventions

Includes tests for:

• Logger injection
• Route-specific scope behavior
• Structured JSON logging output

No breaking changes. All existing logger logic remains untouched.