refactor(core): hard-rename provider definition APIs - #1716

Summary

AgentV's core provider-definition API now matches the supported providers authoring surface instead of exposing target-era configured-provider names. Current repo consumers use ProviderDefinition, ResolvedProviderBackend, readProviderDefinitions, listProviderLabels, resolveProviderDefinition, and resolveDelegatedProviderDefinition; the old target-named exports were removed rather than kept as deprecated aliases.

This is scoped to the configured-provider API slice. Runtime/artifact compatibility fields such as result target, SDK target proxy/client names, and broader CLI selection internals remain intentionally deferred to the existing follow-up Beads.

Related: Bead av-kfik.53.1

Validation

• bun test packages/core/test/evaluation/providers/targets-file.test.ts packages/core/test/evaluation/providers/targets.test.ts packages/core/test/evaluation/providers/targets-cwd-fallback.test.ts packages/core/test/evaluation/providers/fallback-targets.test.ts packages/core/test/evaluation/providers/pi-runtime.test.ts
• bun test packages/core/test/evaluation/loaders/config-loader.test.ts packages/core/test/evaluation/yaml-parser.test.ts apps/cli/test/commands/eval/targets.test.ts apps/cli/test/commands/eval/run-command-options.test.ts apps/cli/test/commands/eval/task-bundle.test.ts apps/cli/test/commands/eval/bundle.test.ts
• bun --filter @agentv/core typecheck
• bun --filter agentv typecheck
• bunx biome check $(git diff --name-only)
• git diff --check
• rg scan confirmed the removed exact exported names are absent from packages/core, apps/cli, and the current custom provider docs.

Code review: skipped because this is a mechanical exported-symbol rename with no behavior logic change.

Post-Deploy Monitoring & Validation

No additional operational monitoring required. This is a compile-time API rename in TypeScript source and docs; CI typecheck, tests, and lint are the merge gate.