fix(hydra-gates): stop claiming OCA\OpenRegister\Contract\ as a runtime psr-4 prefix

[rubenvdlinde]

⛔ Blocked on the four consumer guards below. This composer.json reaches an app only when that app bumps to a release containing it — so merging early leaves the fleet one composer update from a bootstrap fatal.

• fix(tests): opt into the OpenRegister contract instead of relying on a claimed prefix buildiq#306
• fix(tests): opt into the OpenRegister contract instead of relying on a claimed prefix decidiq#829
• fix(tests): opt into the OpenRegister contract instead of relying on a claimed prefix filinq#717
• fix(tests): opt into the OpenRegister contract instead of relying on a claimed prefix stackiq#696

---

Closes #531.

The package declared:

"autoload": { "psr-4": { "OCA\\OpenRegister\\Contract\\": "hydra-gates/contracts/" } }

That prefix is longer than openregister own OCA\OpenRegister\ to lib/, PSR-4 is longest-prefix-wins, and the package installs into every consumer vendor/ — so whichever app autoloader registered first defined OpenRegister contract for the whole process. Measured on a real instance: softwarecatalog vendored copy was supplying openregister own interface, and a v1.8.0 copy without patchObject() broke callers of the real one (#514).

The contracts still ship; consumers opt in from their own test bootstrap behind interface_exists(), which is order-independent. A fallback autoloader does not work — spl_autoload_register appends relative to registration order, and that order across independently loaded apps is exactly what nobody controls.

The migration is FOUR apps, not the fourteen #531 estimated

Measured by cloning all eighteen and grepping, rather than by code search (which rate-limits and returns unreliable zeros):

category	apps
needs the opt-in	buildiq, decidiq, filinq, stackiq
ships its own contract stubs	dossiq, pipelinq, shillinq
owns the real one	openregister — resolves from lib/Contract/ before and after
never references it	the remaining ten

Each of the four is verified both directions — prefix present (guard no-ops) and prefix removed (guard supplies) — by editing the vendored package entry in vendor/composer/installed.json. Editing the vendored composer.json does nothing; Composer reads installed.json, which cost one invalid experiment before I noticed.

stackiq was not preparation at all

Its bootstrap-unit.php maps only OCA\OpenRegister\Db\ and ...\Service\, never ...\Contract\ — so its standalone unit suite was already failing on this:

state	result
before	Tests: 715, Assertions: 2573, Errors: 131, Failures: 1
after	Tests: 715, Assertions: 2993, Errors: 1, Failures: 0

The remaining error is unrelated (absent Symfony\Component\HttpFoundation\HeaderUtils).

Docs updated: hydra-gates/README.md gains the opt-in snippet with the two traps (put it before anything implementing the interface; put it in the bootstrap phpunit.xml actually loads — several apps ship two or three), and docs/hydra/operations/app-health.md records that the mechanism is gone.