test(smoke): fix three stale assertions (#3)

- 01 calculator: page lives at /calculator/ (confirmed live), not
  /reconstitution-calculator/ — the 404 failed all 3 calc tests.
- 00 homepage: brand title is 'Peptide Repo' (with space); regex /peptiderepo/i
  never matched. Broadened to /peptide ?repo/i.
- 03 admin: required-plugin slug is 'prautoblogger' (WP dir), not 'pr-autoblogger'.

These were test bugs, not site regressions — the site serves all three correctly.

Agent-Session: cto smoke-triage

Co-authored-by: peptiderepo <peptiderepo@users.noreply.github.com>

tests/03-admin-plugins.spec.ts

@@ -25,7 +25,7 @@ const REQUIRED_PLUGINS = [
   'peptide-search-ai',
   'peptide-repo-core',
   'peptide-reconstitution-calculator',
-  'pr-autoblogger',
+  'prautoblogger',
   'peptide-starter-theme', // theme, shown differently — checked separately
 ];