fix: handle non-standard HTTP methods in router

[lunadogbot]

Summary

Fixes #3804.

Production apps crashed with TypeError: handler2 is not a function when a request arrived with a non-standard HTTP method such as PROPFIND (common from WebDAV scanners hitting public Fresh sites).

The router's match() method indexed byMethod with the request method and treated the result with item !== null. RouteByMethod<T> only declares entries for the seven known methods (GET/POST/PATCH/PUT/DELETE/HEAD/OPTIONS), so for any other verb byMethod[method] was undefined — which slipped past the !== null check and surfaced as methodMatch: true with item: undefined, crashing the request pipeline.

Normalize the lookup with ?? null in both the static and dynamic branches so unknown verbs route through the existing DEFAULT_NOT_ALLOWED_METHOD path and return a 405.

Tests

• Two unit tests in router_test.ts for PROPFIND against static and dynamic routes — assert methodMatch: false, item: null.
• One integration test in app_test.tsx exercising the full app handler with PROPFIND on both a static and a dynamic route — asserts a 405 response and that nothing throws.

deno task ok passes locally (fmt, lint, type check, full test suite, docs check).

Test plan

• Unit tests for non-standard method on static + dynamic routes
• Integration test for the full request pipeline returning 405
• deno task ok passes locally

Closes bartlomieju/orchid-inbox#63

[lunadogbot]

The canary CI failures are unrelated to this PR — they're a Deno canary regression around node: scheme resolution during Vite SSR module loading.

All 9 failing tests are in packages/plugin-vite/tests/dev_server_test.ts, packages/plugin-vite/tests/build_test.ts, and www/main_test.ts (which uses buildVite). The error is:

TypeError: Unsupported scheme "node" for module "node:assert". Supported schemes: blob, data, file, http, https, jsr, npm
  at async eval (file:///...node_modules/.deno/rollup@4.55.1/node_modules/rollup/dist/es/rollup.js:14:8)

The same canary failures appear on unrelated PR #3807 (no router changes). This PR's v2.x suite passes on all three platforms, and the new router tests (UrlPatternRouter - non-standard method on static route and ... dynamic route) pass locally on stable Deno.

This PR only touches packages/fresh/src/router.ts and the two test files — no Vite plugin changes.