Bun parity: complete HTTP/2 diagnostics and performance telemetry

Tracks follow-up work from #66.\n\nCurrent limitation:\n- HTTP/2 performance entries use synthetic or test-conditioned values rather than session counters\n- server stream close diagnostics remain quarantined\n- stream identity, close versus destroy state, reset code, and push-stream publication need end-to-end semantics\n\nAcceptance criteria:\n- publish HTTP/2 client and server diagnostics channels at lifecycle-accurate points\n- publish distinct server and client stream identities, including pushed stream peers\n- preserve closed, destroyed, rstCode, headers, flags, and error state in diagnostic messages\n- derive performance entry values from real session and stream counters\n- remove the remaining diagnostics server-stream close expectation\n- keep all existing diagnostics and perf_hooks HTTP/2 corpus tests green\n\nParent tracker: #66

Stage 1 is implemented locally in 599d938: shared Http2Stream now inherits Duplex, normal client/server streams have distinct ClientHttp2Stream and ServerHttp2Stream brands, normal created/start/finish/error/close publication is centralized and exactly-once guarded, clean versus error terminal state is covered, and diagnostics channel cache resets with the test runtime. Focused diagnostics passes 2/2 and cumulative HTTP/HTTP2 passes 53/53. Push-peer separation and bodyChunkSent/bodySent remain stage 2 before closing this issue or removing the clean server-close expectation.

Stage 2 is implemented locally in be0d241 (feat(runtime): complete HTTP2 diagnostics telemetry), with expectation cleanup in 301e857. Home now creates distinct linked client/server push-stream peers in both normal and compatibility paths; preserves endpoint session, stream ID, Duplex branding, reset/cancel, and reservation cleanup semantics; publishes created/start/finish/close-or-error exactly once; emits exact bodyChunkSent payloads for string, buffer, writev, and mixed writes; and publishes bodySent once after all chunks, including empty bodies.\n\nVerification completed before the next parser tranche began: focused diagnostics 2/2 and every maintained bootstrap HTTP2 group 31/31. Three now-covered diagnostics failures and eight stale maintained HTTP2 hang skips plus three orphan sequential skips were removed. ASAN markers remain intentionally untouched pending real instrumentation.