feat(subgraph): built-in retry with exponential backoff for subgraph queries

[addnad]

What

Adds a built-in retry mechanism with exponential backoff to SubgraphClient, so transient subgraph/gateway failures no longer surface instantly as errors to downstream apps.

• Retryable: network errors (fetch rejection), HTTP 5xx, invalid/truncated response bodies
• Never retried: HTTP 4xx (incl. 400 Bad Request), GraphQL-level errors
• Backoff: 500ms → 1s → 2s (base configurable via retryDelay)
• Configurable: SubgraphClientOptions.retries (default 3) and retryDelay (default 500); retries: 0 opts out entirely

All retry logic lives in rawQuery, so every public method (getTopTraders, getTrades, getVaultSnapshots, getSyncStatus) benefits automatically. Existing error messages and WhiteChainError semantics are preserved.

Note: the issue lists src/api/graphqlClient.ts as the likely affected file — that path doesn't exist in the repo; the actual data-fetching module is src/subgraph/Client.ts, which is what this PR modifies.

Acceptance criteria

• ✅ Failed queries automatically retry up to 3 times by default
• ✅ 400 Bad Request errors are not retried (test: single fetch call, immediate throw)
• ✅ Unit tests mock network failures and verify the backoff timing with fake timers (499ms → no retry, 500ms → retry; 1s; 2s)

Also: package.json repair (required)

package.json on main is not parseable JSON (missing }, after the ./zk export block; stray vitest/ws entries inside peerDependenciesMeta), so no npm script can run at all on a clean checkout. This PR repairs it minimally, matching the lockfile (ws → devDependencies, duplicate vitest dropped). Without this, the required local verification (npm run build, tests) cannot even start.

Verification

npx vitest run tests/subgraph/
Test Files  2 passed (2)
Tests  14 passed (14)   ← 8 new retry tests + 6 existing, all green

Full-workspace npm run build still fails on main-pre-existing syntax errors in unrelated files (src/utils/index.ts:13-15, tsconfig.esm.json:11) — verified present on a clean checkout before this change; left untouched as they're outside this issue's scope (and possibly other campaign issues).

Closes #149