fix(runtime-host): preserve transcript projection diagnostics

[jackeyfaker77]

Summary

Durable transcript projection failures currently discard the read model's hard diagnostics and throw only "projection is incomplete". Preserve them in RuntimeReadModelError and include session/invocation context, diagnostic codes, event IDs, and reasons in its message so boundedFailureDiagnostic can record the cause. Raw diagnostic detail stays out of the message; existing log redaction and truncation still apply. Soft diagnostics remain readable, and client error responses are unchanged.

This complements the page/bootstrap logging changes in #5573 and #5600. Test fixtures also close their database stores before cleanup so Windows SQLite locks do not mask assertion failures.

Refs #5572

Verification

• New regressions for unsupported_event, incomplete_event, and tool_use_id_mismatch failed against the original reader; the soft-diagnostic case passed.
• Rebuilt transcript reader and session continuity coordinator suites: 59/59 passed, including both paging directions, diagnostic preservation, redaction, raw-detail omission, and soft-diagnostic reads.
• npm run build, npm run typecheck, npm run lint, and npm run format:check passed.
• Desktop and UI knip checks passed.
• Full-repository npm test was not run.

AI use

• No generative tool made a substantive contribution
• Generative tooling made a substantive contribution

Tool(s) and scope: Codex implemented the diagnostic preservation and regression tests, fixed test database cleanup, ran validation, and prepared this PR.

Checklist

• Tests cover the change and fail without it
• Lint, format, typecheck and the affected suites pass locally

Does this PR entail a change in behavior?

• Yes - described under Summary above
• No