Fix Solcast auth/profile blockers from #317

[andrei-hasna]

Summary

• fix Solcast CLI config to read shared prefixless profile config and legacy connect-solcast fallback without creating files on read
• write Solcast/shared auth credential directories and files with owner-only permissions
• make shared auth status require credential-like stored fields so baseUrl-only profiles are not treated as authenticated
• add focused Solcast and shared auth regression coverage
• restore the root CLI webhooks alias expected by the current test suite with @hasna/events channel commands

References blocked PR #317 and todos task 9f9e2607-ec11-4409-99d2-650cb81ae86f. Parent review task: 4ccddb87-e262-42a8-8724-cdc7b8742b9f.

Validation

• HOME=/tmp/open-connectors-solcast-home TMPDIR=/tmp bun test connectors/solcast/src/api/client.test.ts connectors/solcast/src/utils/config.test.ts -> 10 pass, 0 fail
• rm -rf /tmp/open-connectors-auth-home && mkdir -p /tmp/open-connectors-auth-home && HOME=/tmp/open-connectors-auth-home TMPDIR=/tmp bun test src/server/server-auth.test.ts src/lib/runner-auth.test.ts -> 60 pass, 0 fail
• bun run typecheck -> pass
• bun run build -> pass
• cd connectors/solcast && bun run typecheck && bun run build -> pass
• rm -rf /tmp/open-connectors-test-home && mkdir -p /tmp/open-connectors-test-home && HOME=/tmp/open-connectors-test-home TMPDIR=/tmp bun test -> 1201 pass, 0 fail
• git diff --cached --check -> pass
• staged secrets scan -> no high-confidence credential patterns found

Review

Independent adversarial review found and the commit fixes: legacy fallback credentials not cleared, baseUrl-only Solcast profiles falsely authenticated, and AWS-style credential env vars no longer counting as configured.

GitHub author is andrei-hasna
GitHub reviewer pool: andrei-hasna, kriptoburak
Selected non-author reviewer: kriptoburak