Related issue: #1262

• Change "Discover an agent" on home page to "Discover agents" and add this subtext underneath: "See working agents in action and try them instantly."

• Site name should remain visible when sidebar is collapsed (NOTE: decision is that author name should NOT be included in header before agent name). It should just be "site name" and agent name

The following updates are for the "Add agent" modal:

• Rename "Docker image" to "Container image URL" for toggle
• Change display in input bar text to "Enter your agent’s Github repository URL" and "Enter your agent’s container image URL"
• Remove "Close" button to the left of "Save" as it is duplicative to the "X" in the top right
• Change "Import your agent" --> "Add new agent"
• Change "Continue" button --> "Add new agent"
• Default selection should be GitHub
• Change "GitHub" radio button to "GitHub repository URL" to enhance clarity
• Remove the label on top of the input bar

• The welcome message on the home page should not be hard coded to "Welcome to IBM's Agent Testbed". The site title should be a variable that defaults to "Agent Stack", but if an admin configures a custom site name in the deployment settings, that name will be used instead. In that case, both the site title at the top and the welcome message (“Welcome to {site name}”) will reflect the custom name.
• Remove the circle around the settings icon in the bottom left corner