fix(agents): make invocations_ws protocol priority order-independent in loadServiceProtocol

[Copilot]

loadServiceProtocol returned ProtocolInvocationsWS immediately on first match, so a manifest listing invocations_ws before invocations would shadow the higher-priority invocable protocol. The selection should be deterministic regardless of declaration order.

Fix

Changed state.go to track sawInvocationsWS with a flag (same pattern as sawInvocations) instead of returning early. Priority is now enforced post-loop: responses > invocations > invocations_ws.

// Before — order-dependent
case ProtocolInvocationsWS:
    return ProtocolInvocationsWS  // returns early, misses invocations below it

// After — order-independent
case ProtocolInvocationsWS:
    sawInvocationsWS = true
// ...
if sawInvocations {
    return ProtocolInvocations
}
if sawInvocationsWS {
    return ProtocolInvocationsWS
}

Also included (PR #9009 base changes)

• resolver.go: Added ProtocolInvocationsWS = "invocations_ws" constant; suppress invoke hints in appendInvokeLocalSecondary for WS agents (not invocable via azd ai agent invoke)
• init_from_code.go: Added invocations_ws to knownProtocols with version 2.0.0
• init.go: Plumbed --protocol invocations_ws through synthesizeImageManifestFile; default protocol now uses knownProtocols[0] instead of a hardcoded literal
• schemas/azure.ai.agent.json: Added invocations_ws to protocol field descriptions
• hosted-agent-regions.json: Added westus2
• Tests covering single invocations_ws, responses wins over WS regardless of order, invocations wins over WS regardless of order

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