SDK clients expose no `initialize()` bindings and `PriceOracleClient`/`RiskRegistryClient.addVerifier` are stale relative to the deployed contracts' real interfaces

[OxDev-max]

Description

None of the 7 classes in sdk/src/clients.ts (InvoiceNftClient, MarketplaceClient,
FinancingPoolClient, TreasuryClient, RiskRegistryClient, AccessControlClient,
PriceOracleClient) exposes an initialize() method, even though KoraClient's own doc
comment (sdk/src/KoraClient.ts:22-33) presents itself as a general-purpose facade "over all 7
Kora Protocol contracts" — meaning the SDK cannot be used to stand up a protocol instance at
all, only to interact with an already-deployed one wired up by hand via scripts/deploy.sh.

Two existing bindings are additionally stale relative to the real contracts:

• PriceOracleClient.getPrice(asset: string) / setPrice(admin, asset, price)
  (sdk/src/clients.ts:266-277) call get_price/set_price with a single symbol argument.
  The actual contract (contracts/price_oracle/src/lib.rs) requires a (base: Symbol, quote: Symbol) pair for both get_price and set_price — the SDK's single-asset signature
  cannot express a currency pair at all and would fail against the real contract's XDR interface.
• RiskRegistryClient.addVerifier(admin, verifier) (sdk/src/clients.ts:224-230) omits the
  stake_amount parameter that risk_registry::add_verifier now requires
  (contracts/risk_registry/src/lib.rs:142) — the same staking-model gap as issues Fix Reentrancy Guard in Financing Pool Contracts #2, Refactor Treasury Contracts #7, Optimize Financing Pool Contracts #9.

Requirements and Context

Fixing this closes the loop between the contract-side signature fixes (issues #2, #7, #9) and
the SDK: without it, every downstream fix to the Rust side still leaves the TypeScript client
silently broken for anyone building a dApp or ops tool on top of it.

Suggested Execution

1. git checkout -b feature/sdk-client-interface-parity
2. Add an initialize(...) method to each of the 7 client classes, matching each contract's
   current parameter list exactly (cross-reference each contract's pub fn initialize).
3. Fix PriceOracleClient.getPrice/setPrice to take (base: string, quote: string, ...)
   instead of a single asset, and update sdk/src/types.ts if any oracle-related type needs
   a base/quote pair shape.
4. Fix RiskRegistryClient.addVerifier to accept and forward a stakeAmount: bigint.
5. Add the new tests from issue Add Tests for Invoice NFT Contracts #11 covering these corrected/new methods.
6. Update sdk/README.md's usage examples to reflect the corrected signatures.

Acceptance Criteria

• Every one of the 7 SDK client classes exposes an initialize() method matching its contract's current signature
• PriceOracleClient.getPrice/setPrice take a (base, quote) pair, not a single asset
• RiskRegistryClient.addVerifier accepts and forwards stakeAmount
• A test (per issue Add Tests for Invoice NFT Contracts #11's infrastructure) proves each corrected method encodes the right number and type of XDR arguments

Guidelines: PR description must include Closes #<issue-number>.
Complexity: High (200 points)