fix(ai skills): correct stale branch names, rg flags, and commit scope rules

Fixes deslop diffing against nonexistent main, an invalid rg --type tsx flag
in fix-merge-conflicts, a Codex-specific phrase leaking into the Claude/Cursor
inspect-elements description, and aligns commit-format with the required-scope
convention the commit skill and git history already use. Rewrites the readme
skill from 764 lines of Rails-specific guidance to a lean version matching
this Vite/Capacitor/Electron repo.

.codex/skills/you-might-not-need-an-effect/SKILL.md

@@ -12,7 +12,7 @@ Based on https://react.dev/learn/you-might-not-need-an-effect
 
 ## Arguments
 
-- **scope**: what to analyze (default: uncommitted changes). Examples: `diff to main`, `src/components/`, `whole codebase`
+- **scope**: what to analyze (default: uncommitted changes). Examples: `diff to master`, `src/components/`, `whole codebase`
 - **fix**: whether to apply fixes (default: `true`). Set to `false` to only propose changes.
 
 ## Workflow