Faster route matching and request/response fixes

This release adds an opt-in tree-based route matcher. Enable it with router.matcher: 'tree'. The linear matcher remains the default. The tree matcher preserves registration order unless you configure precedence: 'specificity'.

Our benchmarks used 1,000 registered routes. The full-stack HTTP cases matched the last registered route:

Workload	Before (req/s)	After (req/s)	Change	p50 before	p50 after
Dynamic route	38,249.6	75,385.6	+97.1%	29 ms	9 ms
Wildcard route	39,414.4	75,552.0	+91.7%	28 ms	9 ms

Each result is from five rounds, with a 3-second warmup, a 5-second measurement window, 100 connections, and a pipeline depth of 10.

Matcher-only benchmarks reported these speedups:

Scenario	Speedup
Dynamic route at the end	18×
Dynamic route miss	22.8×
Deep dynamic route	12.1×
Wildcard route at the end	18.4×
1,000 overlapping regex matchers	1.19×

These results cover specific workloads, not every route pattern. The PR notes that its full-stack static-route benchmark had not been rerun against the final implementation.

This release also fixes three request and response edge cases.

• Requests behind trusted proxies now use the first X-Forwarded-Host value.
• Redirects without an explicit query-string option follow the server configuration, while false disables forwarding.
• Sending a native Response preserves all its Set-Cookie headers and appends them to cookies already set on the response.