[SonAndE14]

Every APIRepository instance registers a bound plugin-reload listener, but those short-lived repositories never unregister. Opening more pages or searching more providers therefore retains repository/provider instances and makes future reload events iterate over an increasing number of identical shared-cache invalidations.

Register one listener when the companion object's shared response cache is initialized. Preserve the existing behavior: a forced plugin reload clears the cache; an ordinary plugin-loaded event leaves it intact. This does not change provider APIs, cache TTLs or network requests.

Regression validation:

• Added a test that constructs 200 repositories and checks that observer count remains constant. It fails on current upstream, where each construction adds an observer.
• Added a fake-provider test that verifies cached responses are shared across repository instances, survive a non-forced event and are loaded again after a forced event. It passes before and after the change.
• After the fix: all 10 JVM tests passed (8 existing and 2 new). :app:assemblePrereleaseDebug, :app:lintPrereleaseDebug and :library:checkKotlinAbi passed.

AI disclosure: implementation, code review and automated test execution used OpenAI Codex assistance, in accordance with AI-POLICY.md. This contribution is kept separate from the fork's other changes so it can be reviewed independently.