docs: improve accessibility for agents (#3424)

* Improve docs accessibility for agents

Signed-off-by: Alexandros Koumparoulis <akoumparouli@nvidia.com>

* docs: avoid inaccessible code block controls

Signed-off-by: Alexandros Koumparoulis <akoumparouli@nvidia.com>

* docs: label Fern desktop theme controls

Signed-off-by: Alexandros Koumparoulis <akoumparouli@nvidia.com>

* docs: fix desktop Fern accessibility

Signed-off-by: Alexandros Koumparoulis <akoumparouli@nvidia.com>

* docs: name Fern theme menu for assistive tools

Signed-off-by: Alexandros Koumparoulis <akoumparouli@nvidia.com>

* docs: hide inaccessible Fern theme control

Signed-off-by: Alexandros Koumparoulis <akoumparouli@nvidia.com>

* docs(fern): split model support logs by type

Signed-off-by: Alexandros Koumparoulis <akoumparouli@nvidia.com>

* docs(fern): move support logs to overview pages

Signed-off-by: Alexandros Koumparoulis <akoumparouli@nvidia.com>

* docs: generate diffusion support tables

Signed-off-by: Alexandros Koumparoulis <akoumparouli@nvidia.com>

* docs: derive model support from git history

Signed-off-by: Alexandros Koumparoulis <akoumparouli@nvidia.com>

---------

Signed-off-by: Alexandros Koumparoulis <akoumparouli@nvidia.com>