fix(coverage): probe the pwsh exemption with the executor's own resolution

The review caught the pwshCoverageExclusions comment claiming the inverse of
the code's behavior: a bare-PATH probe FAILING grants the exemption, so a
win32 host where only install-location pwsh (or 5.1) resolves kept the
exemption while its suites ran - over-exempting, never tightening.

resolvePwshPath/candidatePwshPaths move to the dependency-free
pwsh-local/src/resolve.ts (index.ts re-exports; public API unchanged) and
vitest.config.ts probes with that shared definition, so the exemption is
active exactly when the suites skip. The two spec headers stop saying
'on PATH' for a probe that is deliberately not PATH-only, and the parity
note records the abort backport as the one both-ways parity change (both
languages, pairing re-recorded); catalogs regenerated for the line shift.

docs/config-catalog.md

@@ -1004,7 +1004,7 @@ export interface Config {
 }
 ```
 
-Source: [`packages/bash/pwsh-local/src/index.ts:55`](../packages/bash/pwsh-local/src/index.ts)
+Source: [`packages/bash/pwsh-local/src/index.ts:54`](../packages/bash/pwsh-local/src/index.ts)
 
 ## `@deepseek-ai/dsh-repeat-tool-guard`