[Pipeline B] Reshape templates & forms contract to B

[abhishek-8081]

Reshapes the templates and forms OpenAPI contract from Pipeline C to Pipeline B (follows the
C-file removal in #645).

Changes:

• forms.yaml: replaced the C endpoints (generate/all, generate/{form_type}, form_by_id, pdf,
  json, batch) with B's real endpoints — POST /forms/fill and POST /forms/jobs.
• form-record.yaml: replaced the C schemas with FormFillRequest/Response and AsyncFormFill*,
  matching app/api/schemas/forms.py exactly.
• templates.yaml / template.yaml: template_id is now integer; removed incident_mapping; kept
  layout (per the team decision); form_type is a plain string.
• enums.yaml: removed FormType, FormStatus, OutputFormat (nothing in the B contract
  references them).
• openapi.yaml: Layer 3 now points at /forms/fill and /forms/jobs.

Contract validates clean (make docs, no broken $ref).

Two intentional scope notes:

• Uses input_text to match the current code. Switching the fill flow to input_id (fill by
  stored transcript) is a separate follow-up issue that moves contract and code together.

• Covers the core fill flow + templates. Operational endpoints (models, transcribe,
  submissions, purge) are intentionally out of scope for this reshape.

  @marcvergees @vharkins1 @chetanr25