feat!: v2.0.0 — ky 2, relay-runtime 21, reworked config, coverage CI

[cliedeman]

Major upgrade landing on top of the open-source-prep base.

• ky upgraded to v2 (peer + dev); migrated to the new beforeError ({error}) signature guarded by isHTTPError, and read HTTPError bodies via ex.data (bodies are now auto-consumed).
• relay-runtime moved to 21 (self-typed); dropped @types/relay-runtime and repointed the internal Sink type import.
• Reworked configuration:
  • queries now sent as GET, mutations as POST (makes the retry methods:["get"] default effective);
  • deleteDataIfError is now a real, honoured option (default true);
  • beforeRequest/afterResponse/beforeError consolidated into a single hooks option;
  • fixed a precedence bug that discarded static headers objects.
• Expanded tests (5 -> 31) and added a defer.spec.ts unit suite.
• Added code-coverage reporting to the GitHub Actions CI workflow.
• Documented all options in the README and added CHANGELOG migration notes. Bumped version to 2.0.0 and engines.node to >=22 (ky 2).

[github-actions]

Coverage Report

Status	Category	Percentage	Covered / Total
🔵	Lines	81.9%	181 / 221
🔵	Statements	82.22%	185 / 225
🔵	Functions	93.1%	27 / 29
🔵	Branches	67.7%	109 / 161

File Coverage

File	Stmts	Branches	Functions	Lines	Uncovered Lines
Changed Files
src/main.ts	82.07%	68.6%	90.47%	81.55%	105, 116, 213, 219-224, 246, 262-265, 267, 270-289

Generated in workflow #2 for commit 9fc9c5c by the Vitest Coverage Report Action