Drop vestigial storage adapter from startOAuthLogin
`startOAuthLogin` never touched the storage adapter it accepted —
the WASM function only resolves the PDS, discovers the AS, generates
DPoP/PKCE/state, fires the PAR request, and returns the auth URL +
serializable pending state. The existing comment in the body even
spells it out: "Config is NOT saved here — the user hasn't authorized
yet."
The parameter was paying for itself in nothing and forcing every SDK
caller to construct a `WasmStorageAdapter` for a no-op. Dropping it:
- Removes `_storage_adapter: JsStorageAdapter` from the WASM extern.
- Removes `storage: Storage` from `StartLoginOptions` in @opake/sdk.
- Drops the `createStorageAdapter(options.storage)` call in
`Opake.startLogin`; adjusts `Opake.login` (which composes start +
complete) to omit `storage` from the start half only — complete
still needs it.
- Web auth store: stops reading `getStorage()` before calling
`Opake.startLogin`.
Downstream callers that were passing storage to `startLogin` will
see a TS error at the call site — the fix is a one-line removal.
No runtime behaviour change; any build that passed storage was just
wasting an adapter allocation per login start.