[adamtheturtle]

Closes #3739.

Package the authoritative Vuforia Web Services and Model Target API contract suite in a separately buildable contract-tests/ project. Shared fixtures and helpers depend on neither the mock implementation nor Flask. A separate test-backends/ development package supplies the explicitly loaded core adapters; other repositories can provide their own adapter plugin.

Import-only compatibility modules retain core CI selectors, marks and fixture bindings. Assertions have one maintained source, coverage measures the packaged implementations, and the 100% gate remains unchanged. Core interception and deployment assertions stay in the core tests.

A pytest consumer integration test builds wheels, collects the installed suite without the implementation or Flask, then runs existing contracts through the explicit Flask adapter from a fresh environment. Checked-in consumer plugins verify dependency isolation, the None-valued setup contract and absence of checkout-test imports. Documentation covers installation, adapter requirements and revision compatibility; Docker and docs builds support the workspace packages.

The five API migrations are merged here: #3807, #3808, #3809, #3810 and #3811.

Validation:

• Migration checks preserve the existing test node IDs and assertion/fixture definitions.
• Final combined local mock suite: 2,030 passed, 833 skipped, including Docker deployment tests.
• The final combined isolated wheel-consumer integration test passes; the individual API-family consumer checks also pass.
• Pre-commit, partition checks, all type checkers and Pylint pass.
• Docker build, runtime import smoke and Sphinx HTML build pass.
• Final-head hosted verification: 120 successful checks, one skipped check, and 100% line/branch coverage. The live query job fails with the previously known ProjectSuspendedError; its completion-ci aggregate also fails. These two failures were explicitly accepted for this merge.