docs(sdk): define ESM module contract

[0xnavarro]

Public change

Document the module-format contract for the first public @brida/sdk release.

• @brida/sdk@0.1.0 is ESM;
• Node 22.0.0 is the supported runtime floor for ESM consumers;
• synchronous CommonJS require('@brida/sdk') is not part of the 0.1 contract;
• CommonJS applications can use dynamic import();
• a parallel CJS build/require export should only be introduced if an explicit compatibility need justifies the additional package surface and is covered at the supported Node floor.

This closes an ambiguity found during pre-publication clean-room testing: current later Node 22 releases may load ESM via require(), but exact Node 22.0.0 correctly rejects it with ERR_REQUIRE_ESM.

Validation

Exact head: 192ab541271abaf1af62d0bc4e95866b3807dd36.

• pnpm check: PASS;
• SDK/release tests: 23/23 PASS;
• repository/release policy tests: 11/11 PASS;
• full-history public leak scan: PASS;
• exact Node 22.0.0 ESM clean consumer: PASS;
• TypeScript NodeNext consumer: PASS;
• TypeScript Bundler consumer: PASS;
• exact Node 22.0.0 synchronous CommonJS require: intentionally not supported and now documented.

Compatibility / risk

Docs/architecture only. Runtime/package exports are unchanged.

Release intent

• release-impact: none
• release-note: Define @brida/sdk 0.1 as an ESM package with Node 22.0.0+ ESM support and no synchronous CommonJS require contract.
• qa-scope: Node 22/24 public CI, SDK/release/policy tests, CodeQL, full-history leak scan, exact Node 22.0.0 ESM consumer and TypeScript NodeNext/Bundler consumers.