Refresh all Canton-sourced snippets to Canton 3.5 (v3.5.1)

[8bitpal]

Goal

Regenerate and refresh all Canton-sourced documentation snippets to Canton 3.5 (released tag v3.5.1, tagged 2026-05-27). The currently embedded snippets predate 3.5 and several pages depend on snippet output that can only be produced by Canton's build.

Background: how Canton snippets work

Canton 3.5 generates most console/config examples through the .. snippet:: directive rather than inline code or .. literalinclude::. The directive holds the commands to run (including .. hidden:: setup lines), not the rendered example. Example from parties.rst:

.. snippet:: party_management
    .. hidden:: bootstrap.synchronizer(synchronizerName = "da", ...)
    .. hidden:: participant1.synchronizers.connect_local(sequencer1, "my-synchronizer")
    ... visible commands ...

Current state

• 356 generated Canton snippet files under docs-main/snippets/external/canton/.
• 44 cf-docs pages import Canton snippets.
• 40 pages (95 COPIED blocks) are still sourced from Canton 3.4.
• The generated tree is keyed to an old Canton ref, not v3.5.1.