Incorporated review comments for A2A support

[aosingh]

Oracle database objects

• Renamed SELECT_AI_A2A_TASKS to DBMS_AI_A2A_TASKS$.
• Renamed SELECT_AI_A2A_CONTEXTS to DBMS_AI_A2A_CONTEXTS$.
• Added read-only views without dollar signs for normal querying.
• Updated SQL and runtime references to use fully qualified database object names.

CLI and architecture

• Unified the standalone server and gateway behind select-ai a2a serve
• Added --deployment standalone|clustered.
• Removed the unreleased select-ai a2a gateway command.
• Kept deployment topology separate from database-connection provisioning.

Database connection and A2UI forms

• Dynamically generates the A2UI form using only fields missing from server configuration.

• In case, the database connection URL and AI Agent is configured a deployment time then the form shows only username and password to the user

• Added custom form support through --a2ui-form. The A2UI form is a simple JSON doc. The SDK provides a default JSON form generator so users get the correct form automatically. --a2ui-form PATH simply replaces that generated JSON with another validated JSON document when a custom layout is needed.

  [
    {
      "component": "TextField",
      "label": "Database username",
      "bind": "username"
    },
    {
      "component": "TextField",
      "label": "Database password",
      "bind": "password",
      "obscured": true
    },
    {
      "action": "submit_database_connection",
      "submit": ["username", "password"]
    }
  ]

OAuth and Cloud Run authentication

• Added a single explicit --require-oauth option.

• Without --require-oauth:

  • The application does not require an Authorization header.
  • Cloud Run IAM can still authenticate the service using X-Serverless-Authorization.
  • A2A conversations are separated using context_id.

• With --require-oauth:

  • Authorization: Bearer ... is required.
  • Bearer authentication is advertised in the Agent Card.
  • Sessions are scoped using authenticated owner plus context_id.