v0.9 Spec: Add identity fields to theme

[jacobsimionato]

This PR updates the v0.9 specification to include iconUrl and agentDisplayName in the standard catalog theme definition.

Changes

• standard_catalog.json: Added iconUrl and agentDisplayName to the theme object.
• a2ui_protocol.md: Added a Theme section under Standard Component Catalog to document these new properties and explain their usage for identifying sub-agents and ensuring security against impersonation in orchestrator scenarios.

[gemini-code-assist]

Code Review

This pull request adds iconUrl and agentDisplayName to the theme definition in the v0.9 specification, enhancing agent identification and security. The changes are well-documented in both the protocol markdown file and the standard catalog JSON schema. My review includes a couple of minor suggestions to improve documentation consistency and fix a formatting issue in the markdown.

[gemini-code-assist]

There's a minor formatting issue in the markdown table. The agentDisplayName property is missing a space before the closing pipe |, which might cause rendering issues in some markdown viewers. Adding a space will ensure the table is correctly formatted.

Suggested change

	| **agentDisplayName**| String | Text to be displayed next to the surface to identify the agent or tool that created it (e.g. "Weather Bot").|
	| **agentDisplayName** | String | Text to be displayed next to the surface to identify the agent or tool that created it (e.g. "Weather Bot").|

[gemini-code-assist]

For consistency with the documentation in a2ui_protocol.md, consider adding the examples to the descriptions of iconUrl and agentDisplayName. This provides more context for developers using the schema directly and ensures both documents are aligned.

Suggested change

	"iconUrl": {
	"type": "string",
	"format": "uri",
	"description": "A URL for an image that identifies the agent or tool associated with the surface."
	},
	"agentDisplayName": {
	"type": "string",
	"description": "Text to be displayed next to the surface to identify the agent or tool that created it."
	}
	"iconUrl": {
	"type": "string",
	"format": "uri",
	"description": "A URL for an image (e.g., logo or avatar) that identifies the agent or tool associated with the surface."
	},
	"agentDisplayName": {
	"type": "string",
	"description": "Text to be displayed next to the surface to identify the agent or tool that created it (e.g. \"Weather Bot\")."
	}