[FEATURE] Capture adapter initialize capabilities + best-effort exceptionInfo enrichment on exception stops

[debugmcpdev]

Follow-up to #220 (breakOnExceptions shipped without runtime capability negotiation).

Gaps

1. The DAP initialize response is discarded (dap-proxy-connection-manager.ts, initializeSession) — the adapter's real Capabilities (exceptionBreakpointFilters, supportsExceptionInfoRequest, supportsExceptionFilterOptions, ...) are unavailable at runtime. [FEATURE] No way to enable break-on-exception — uncaught exceptions terminate instead of pausing #220's per-language filter tables live on the adapter policies instead; capturing capabilities would let us validate the resolved filters against what the live adapter actually declares (and warn on drift — the static getCapabilities() declarations have already drifted once, see the js-debug correction in [FEATURE] No way to enable break-on-exception — uncaught exceptions terminate instead of pausing #220's PR).

2. DAP exceptionInfo is never requested. On a stopped with reason: 'exception', a best-effort exceptionInfo call (gated on the captured supportsExceptionInfoRequest, failures swallowed) could enrich lastStop with exceptionId, breakMode, and the full stack description beyond the description/text fields the stopped event carries today. debugpy, js-debug, and netcoredbg all support it.

Sketch

• Capture the initialize response body in the worker, forward it to the SessionManager in the adapter_configured status (or a dedicated message), store on ManagedSession.
• On exception stops, worker (or SessionManager via sendDapRequest) issues exceptionInfo(threadId) when supported and merges the result into lastStop.