fix(appkit): match parameterized raw body paths

[fallintoplace]

Summary

• match skipBodyParsing route templates with :param path segments against real request paths
• keep exact raw-body path matches as the fast path
• strengthen server tests so JSON requests prove body parsing is skipped

Root Cause

Plugin routes store raw-body skip paths as full route templates, for example /api/files/:volumeKey/upload. The server JSON parser only compared the runtime request path with exact string equality, so /api/files/uploads/upload did not match the registered template and JSON parsing could consume upload request bodies before the raw stream handler.

Validation

• pnpm exec vitest run packages/appkit/src/plugins/server/tests/server.test.ts
• pnpm exec biome check packages/appkit/src/plugins/server/index.ts packages/appkit/src/plugins/server/tests/server.test.ts
• pnpm --filter @databricks/appkit typecheck
• git diff --check