fix(router): remove setInitialState override pattern from SPA navigation

[mohamedmansour]

The router previously checked for a user-defined setInitialState method on route components and fell back to applyStateAsAttributes when absent. This created two problems:

1. App developers were overriding setInitialState to manually assign @observable and @attr properties — duplicating what the framework base class already does automatically. Every override was a potential source of bugs (missed properties, wrong types, stale state).

2. Route params (e.g. :folderId, :threadId) were passed as a second argument to setInitialState, mixing concerns. Params are HTML attributes that @attr reflects; state is JSON that @observable consumes. These are two different mechanisms.

Changes:

• Router now always calls the framework's built-in setInitialState(state) which sets @observable properties and synchronously flushes DOM updates via (). No override needed or supported.

• Route params are set as HTML attributes (kebab-case) before setInitialState, so @attr reflection handles them automatically. E.g. params.threadId becomes attribute thread-id on the element.

• Removed applyStateAsAttributes fallback — the framework's setInitialState + \ handles all cases: scalars via @observable setters, arrays/objects via complex property bindings with synchronous child flush.

• Moved isInitialNavigation flag before async work to prevent a race condition where a user click during SSR bootstrap component loading could re-enter the initial navigation path.