RodexDB v0.5.1

Added

• Single canonical contract — contract/rodex-contract.json is now the
  one source for every public limit/capacity value (NORMAL + PERFORMANCE
  budgets, 400 KB item cap, batch/query/admin caps, storage, MCP budgets).
• Deterministic generator — npm run contract:generate produces the
  gateway + dashboard typed modules, generated Markdown tables, README limit
  row, and OpenAPI x-rodex-capacity metadata from that one file.
• Drift guards — npm run contract:check fails CI when generated output
  is stale, active pages/docs contain old public numbers, or the contract is
  invalid (contract parity tests added; 182 gateway tests).
• docs/generated/ reference tables + generated sections embedded in
  docs/capacity.md, docs/rate-limits.md, docs/mcp.md; ADR-007;
  docs/contract-maintenance.md guide.

Changed

• Gateway + dashboard now import public limits from the generated contract
  module (runtime values unchanged — NORMAL 800/800/2 000/2 400, PERFORMANCE
  100 000/400 000/500 000/2 000 000, 400 KB cap, 50-batch, 100-query).
• Package versions aligned to 0.5.1 (root, gateway, dashboard, rodexdb, rodex-mcp).

Tests

• 182 gateway tests (179 prior + 3 contract-parity).