refactor(errors): standardize unknown-error normalization across the repository (#238)

[s6pa1rta3n-lab]

Summary

Resolves #238.

Standardizes unknown-error handling and normalization across all workspace packages, background services, and the web application.

Key Deliverables

• Created @sub-rosa/errors package with dual ESM/CJS exports and tree-shaking support:
  • normalizeError: Converts any thrown unknown value (Error instances, thrown primitives, plain objects, nested causes, circular structures) into a strongly typed NormalizedError.
  • getErrorMessage and getPublicErrorMessage: Provide safe message extraction with secret scrubbing and actionable user guidance for Soroban contract codes.
  • Secret redaction: Recursively redacts bearer tokens, Stellar secret keys, PEM private keys, URL credentials, and sensitive property keys.
  • Test suite: 39 unit tests validating classification, normalization, snapshot-free assertable models, and redaction.
• Added repository guard scripts/check-error-normalization.mjs and test suite scripts/check-error-normalization.test.mjs:
  • Enforces uniform error handling across packages/, services/, and apps/.
  • Blocks antipatterns such as unnormalized instanceof Error ternaries and raw String(e) coercions.
  • Configured root scripts errors-pkg:test, errors-pkg:typecheck, errors:guard, and errors:guard:test.
• Migrated error handling call sites:
  • packages/sdk: preflight.ts, mainnet-readiness.ts.
  • packages/tlock: auditor-recovery-cli.ts.
  • services/keeper: queue.ts, keeper.ts, status.ts, watch-loop.ts, status-server.ts.
  • services/appraisal-api: server.ts.
  • services/receipt-cli: index.ts.
  • apps/web: chain.ts, demoActions.ts, useLiveRound.ts, useDrandCountdown.ts, useRoundSession.ts, useDashboardData.ts, PasskeyPanel.tsx, AuditorView.tsx, AttackDemo.tsx.
• Integrated with repository weighted line coverage gate (89.53% coverage on @sub-rosa/errors).

Verification

• pnpm errors-pkg:test (39 tests pass)
• pnpm errors-pkg:typecheck (clean)
• pnpm errors:guard (0 violations)
• pnpm errors:guard:test (5 tests pass)
• pnpm sdk:test (211 tests pass)
• pnpm sdk:typecheck (clean)
• pnpm tlock:test (67 tests pass)
• pnpm tlock:typecheck (clean)
• pnpm keeper:test (73 tests pass)
• pnpm keeper:typecheck (clean)
• pnpm appraisal:test (49 tests pass)
• pnpm appraisal:typecheck (clean)
• pnpm receipt-cli:test (19 tests pass)
• pnpm receipt-cli:typecheck (clean)
• pnpm web:test (81 tests pass)
• pnpm web:typecheck (clean)
• pnpm coverage:test (79.57% weighted coverage vs 70.00% gate, passed)

Payout Routing

• EVM (Base/Arbitrum/Polygon/ETH): 0xF46C9F6d70C50BF81ef3588AB523a90a594a2F89
• Stellar: GCL6OXAMLD75BMTINA6EMRUDWK5THQUSHMYNLSNBCJAPZJHNYJTUNIBC