07: Reduce the API section to REST

[mnocon]

Ticket 07 of the Cohesivo SaaS conversion. Base: saas-batch-3.

A developer opening the API documentation now finds REST and nothing else. There
is no PHP API to be led towards, no generated PHP class reference to be sent
into, and no GraphQL section. REST usage, REST authentication, the generated
REST reference and the OpenAPI schema remain and are the section's whole
content.

This is the largest single deletion in the conversion.

Changes

• 3,651 files deleted: docs/api/php_api/ in full (3,621 files — 1 page
  plus 3,620 files of generated phpDocumentor output), 29 further pages (event
  reference, GraphQL, REST extension points, the PHP API dashboard service page,
  the PHP tracking API page), and one orphaned image.
• 182 files modified: 180 pages, plus mkdocs.yml and lychee.toml.dist.

The 162-file link removal was mechanical

The notes predicted a sed would handle the pages linking into the generated class
reference, and it did. One correction: grep -rl php_api_reference matched
156 files, not 162 — the other six live inside pages this ticket deletes, so
they went with the deletion. The sed left exactly the one predicted residual (a
tuple cards() entry in translations_management.md), removed by hand. The
ticket's "~117 search reference pages" figure was accurate.

Judgement calls

• Nav: the REST API: group is flattened into API:. Nothing was left with
  a single child, so the collapse rule forced nothing — this is the "REST is the
  whole section" reading. The edit is confined to the API: block so it merges
  against the sibling tickets.
• php_api.md#service-container links were repointed at the Symfony
  documentation at all 12 sites, not just the four the notes named. Uniform
  beats leaving half the pages repointed and half unlinked.
• Three passages whose entire content was a pointer into the deleted space were
  deleted rather than unlinked: the advanced-tracking section in
  raptor_connector_guide.md, the ### GraphQL integration section in
  relationlistfield.md, and the taxonomy-events note in taxonomy_api.md.
• GraphQL prose was reworded in three surviving MCP pages, where a GraphQL
  mention would now be a dangling promise.
• In two pages ticket 09 deletes, links were removed but their firewall prose was
  left alone rather than duplicating 09's work.

Residue that needs an owner

docs/content_management/field_types/field_type_reference/matrixfield.md carries
a whole ## GraphQL field type operations section with three ```graphql blocks.
No ticket names it and it contains no link into the deleted tree, so it
survives here and will read as a live GraphQL feature until someone removes it.
Flagged for ticket 16. Smaller GraphQL mentions also survive in
integrated_help.md ("the GraphQL console") and on the edition pages that
tickets 03/05 own.

Separately, the FieldValueCriterion::COMPARISON_* constant bullets in the
search reference lost their links and are now unbackticked plain text —
grammatical but plain. Tickets 14–17 revisit those pages.

Verification

• mkdocs build --strict → exit 0, zero warnings.
• pytest -q → 95 passed (this branch predates ticket 01's five new tests).
• Grep of the built site/ for php_api, event_reference, api/graphql and
  extending_rest_api hrefs returns nothing, and the search index is clean too.

Ticket 21 depends on this one: it removes the tooling that produced the
generated reference deleted here.

🤖 Generated with Claude Code

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