fix: use exported controller stateChange events

[salimtb]

Replace locally constructed stateChanged messenger types with the exported stateChange events from AccountTreeController, ClientController, and NetworkEnablementController to fix typing mismatches in consumers.

Explanation

References

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

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Note

Medium Risk
Wrong event names could have left asset tracking idle on account-tree init, network enablement, or UI/keyring lifecycle; the fix restores those triggers but should be validated in integration.

Overview
AssetsController now wires messenger subscriptions and allowed-event types to the canonical stateChange events exported by AccountTreeController, ClientController, and NetworkEnablementController, instead of locally invented :stateChanged aliases built with ControllerStateChangedEvent.

Runtime subscriptions in AssetsController (account tree init, enabled networks, UI open + keyring lifecycle) and the test mock messenger event list are updated to match. Tests publish ClientController:stateChange, AccountTreeController:stateChange, and NetworkEnablementController:stateChange accordingly. The duplicate NetworkEnablementController:stateChanged entry is removed from the mock.

Changelog records this as a fix for consumers with typing mismatches (#9478).

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