v1.0.0: stable release gate

[SisyphusZheng]

Parent: #30

Scope

• API surface frozen
• Migration guide complete
• All docs examples aligned with frozen API
• All P0/P1 roadmap issues closed or explicitly deferred
• 7 days without P0 regression after RC

Gates

• deno task typecheck
• deno task graph:check
• deno task docs:check-current
• deno task dist:check-object-object
• deno task test
• deno task build
• deno task test:e2e