feat(azure.ai.agents): add invocations_ws (WebSocket) protocol support

[Copilot]

Adds invocations_ws as a supported protocol in the azure.ai.agents extension, and refactors the protocol resolution path to eliminate a redundant protocolInfo→ProtocolVersionRecord conversion.

Core changes

• init_from_code.go: Adds invocations_ws (2.0.0) to knownProtocols; extracts resolveKnownProtocols() returning []agent_yaml.ProtocolVersionRecord directly so callers no longer need a conversion loop; promptProtocols delegates its flag-path to resolveKnownProtocols
• init.go: Adds protocolRecordsForImageManifest() for the --image flow with an explicit rejection of activity (which is only valid for code-deploy init); updates synthesizeImageManifestFile to accept flagProtocols; updates --protocol help text
• hosted-agent-regions.json: Adds westus2
• schemas/azure.ai.agent.json: Adds invocations_ws to ProtocolVersionRecord.protocol description

Tests

• TestKnownProtocolNames — asserts invocations_ws is listed
• TestPromptProtocols_FlagValues/invocations_ws_only — flag path resolves correct version
• TestPromptProtocols_Interactive/websocket_protocol_selected — interactive selection works
• TestPromptProtocols_ChoicesIncludeInvocationsWsWithoutChangingDefault — invocations_ws appears in choices but default remains responses
• TestSynthesizeImageManifestFile_{UsesFlagProtocols,RejectsUnknownProtocol,RejectsActivityProtocol}
• TestCreateAgentAPIRequest_CodeDeploy_InvocationsWsUsesProtocolVersions

[azure-pipelines]

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