feat: add state inspection, split routing, and privacy primitives

[Hahfyeex]

Summary
This pull request combines the four requested Sorokit core improvements:

Adds typed Soroban contract state snapshots, deterministic state digests, key-level added/removed/changed diffs, and an invocation inspection wrapper.
Adds a safe ScVal argument optimization layer that canonicalizes repeated values, preserves positional semantics, reports encoding statistics, and is integrated into prepareContractCall.
Adds a deterministic multi-path strict-receive split planner that ranks quoted routes by effective source cost, respects route capacities, and returns executable payment legs with structured liquidity errors.
Adds browser-compatible zero-knowledge proof infrastructure with claim commitments, proof envelopes, selective-disclosure metadata, and pluggable verification for private transaction validation.
Tests and validation
New focused Vitest suite passes: 7 tests passed.
ESLint passes for all changed TypeScript files.
git diff --check passes.
Full npm run typecheck reaches only pre-existing strict-null errors in src/soroban/nftMetadata.ts, src/transaction/bundles.ts, and src/transaction/priceSubscriptions.ts.
The bundle’s JavaScript build succeeds, but declaration generation is blocked by the pre-existing nftMetadata.ts error; this is documented here rather than changed as unrelated scope.
Closes #469
Closes #462
Closes #463
Closes #466

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