Add typed remote-target lifecycle and invocation support

[terjekv]

Gap

All eight v0.0.9 remote-target operations are currently generic:

• list/create/get/update/delete targets;
• invoke a target as an asynchronous task;
• target events, history, and as-of reads.

Remote targets combine configuration, outbound invocation, tasks, and audit state, so untyped dictionaries are especially error-prone.

Acceptance criteria

• Add RemoteTargetId, strict create/update/invoke request models, and forward-compatible response/result models.
• Expose cursor-aware sync/async remote-target CRUD and invocation services.
• Return the existing typed Task and integrate task details/results without leaking response or configuration secrets.
• Add typed audit/history methods or integrate with the shared audit/history service.
• Redact URLs with credentials, authentication configuration, secret references, sensitive headers, and response bodies from representations and exceptions.
• Add unit and safe pinned-server lifecycle coverage.
• Document SSRF-related server constraints, task semantics, output limits, and audit behavior.