Generate network-tab pages from hidden src templates

This pull request moves the source of the 14 network-tab pages into hidden, editor-visible templates under docs-main/src/, so each published page is fully generated instead of mixing hand-edited prose with generated tabs. Published content is unchanged apart from a "Generated from" notice; direct edits to generated pages fail validation.

Closes #1910. Closes #1673.

Screenshots

Template (hidden page): docs-main/src/global-synchronizer/deployment/required-network-parameters.mdx opens under the hidden "Page templates" product, showing raw |token| placeholders and the callout that marks the network-specific block. It carries noindex and is absent from the product menu on normal pages.

Published page: the generated required-network-parameters page renders the same DevNet/TestNet/MainNet tabs with substituted values as before.