feat(rpiv-pi): drop validate's subagent dispatches; run the pattern check inline

Validate no longer spawns codebase-analyzer + codebase-pattern-finder
(Agent leaves its allowed-tools). A run-history audit of 64 validate runs
(127 dispatches, ~4.8M tokens) found 80% pure rubber stamps and only 2
verdict-affecting catches — both stale references and invalidated
statements left in comments and docs. That earning class is now an
inline step: compare new files against established siblings for shape,
grep for renamed/removed terms lingering in comments, docs, or test
descriptions. Generic checks only — the skill ships to every rpiv-pi
project. Site spec content updated to match.