Unify streaming/WebSocket routes into http_router with path params

[stephenberry]

Summary

Addresses the design feedback in #2550 (from @JnCrMx). Moves streaming and WebSocket route storage off http_server's flat path → handler maps and into basic_http_router, where they share the radix-tree matcher with normal routes. As a result, streaming and WebSocket routes now support :param and *wildcard path segments, and routers carrying any mix of route kinds can be passed to server.mount().

The requested API now works:

glz::http_router router;
router.get("/users/:id/profile", normal_handler);
router.stream_get("/users/:id/events", streaming_handler);
router.websocket("/rooms/:room/ws", ws_server);

glz::http_server server;
server.mount("/api", router);

What changed

• Extracted route_table<H> from basic_http_router; the router now holds three of them (normal_routes, streaming_routes, websocket_routes) sharing one radix-tree implementation.
• New router methods: stream, stream_get, stream_post, websocket, match_streaming, match_websocket.
• http_server::stream* / http_server::websocket delegate to root_router. The flat streaming_handlers_ and websocket_handlers_ maps are removed.
• mount() propagates all three route kinds; each is rewritten with the mount prefix and added to the server's root router.
• Hot-path fast-path: process_full_request_with_conn skips the streaming match when no streaming routes are registered, restoring per-request cost for the common case.
• Bug fixes picked up during the refactor:
  • route_table::match_node now erases the wildcard capture on every failure path (was leaking on is_endpoint=false, wrong method, or constraint failure — parity with the existing :param branch).
  • route_table::add installs in the radix tree first, then populates the routes map, so a route conflict thrown from add_route no longer leaves a half-registered entry that iteration sees but match() never reaches.

Behavior change

Previously streaming_handlers_ was an exact-path map, so stream_get(\"/items/:id\", ...) was effectively dead and a request to /items/42 fell through to the normal router. After the unification, streaming routes are matched before normal routes, so a streaming /items/:id will intercept requests that a normal /items/42 would otherwise handle. Documented in docs/networking/http-router.md (Streaming Routes section + Route Priority section).

Migration

router.routes (public field) is now router.normal_routes.routes. A routes() accessor method is provided for source compatibility (a reference data member would dangle through the implicit move constructor). Updated callers: http_server::mount, http_server::enable_openapi_spec, tests/networking_tests/openapi_test, and docs/networking/rest-registry.md.

Test plan

• Streaming path-param coverage in tests/networking_tests/http_chunked_test/http_chunked_test.cpp: :param direct on server, :param via http_router + mount(), mixing normal + streaming on one router, wildcard segment, :param + query string combo, URL-decoded :param, route_spec::constraints rejection (200 vs 404).
• WebSocket path-param coverage in tests/networking_tests/websocket_test/websocket_client_test.cpp: :param direct on server, :param via router + mount, wildcard segment, all-three-kinds (normal + streaming + WebSocket) coexisting on one mounted router.
• Replaced bare sleep_for(200ms) server-readiness waits in the new streaming tests with a TCP-connect-probe helper for robustness on busy CI.
• Suites pass:
  • http_chunked_test: 57/57 tests, 230 asserts.
  • websocket_client_test: 34/34 tests, 146 asserts.
  • http_router_test: 21/21 tests, 81 asserts.
  • http_server_api_tests: 49/49 tests, 152 asserts.
  • openapi_test: 1/1 tests, 5 asserts.
• clang-format pass on touched headers and test files.

Docs updated

• docs/networking/http-router.md — new "Streaming Routes" and "WebSocket Routes" sections; "Route Priority" extended to cover cross-kind dispatch order.
• docs/networking/http-server.md — mount() propagation note in "Mounting Sub-routers".
• docs/networking/advanced-networking.md — router.websocket(...) + path-param note in the WebSocket section.
• docs/networking/rest-registry.md — field rename in the endpoint-discovery example.