feat: add core/ tier reflecting actual universal workflow

The original repo presented everything as equal rules. In reality, the
workflow has two tiers: core practices (used in every project) and advanced
rules (only in complex projects like Mortdecai).

Core tier adds:
- backup-before-edit (global CLAUDE.md rule)
- superpowers-workflow (the actual workflow engine)
- memory-system (persistent feedback and project memories)
- document-hierarchy (CLAUDE.md/SESSION.md/CONTEXT.md/IDEA.md)
- commit-and-push discipline
- feedback-driven behaviors

Updated README, docs, and dynamic-methodology to reflect the two-tier
reality instead of presenting advanced rules as universal.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -4,13 +4,28 @@ This repository contains a shareable AI-assisted development workflow. It is a r
 
 ## What This Is
 
-A collection of rules, templates, hooks, and methodology guides for working with AI coding assistants (Claude Code, etc.). The rules in `rules/` are designed to be copied into `.claude/rules/` in any project.
+A two-tier workflow system for AI coding assistants (Claude Code, etc.), reflecting how the workflow is actually used across 26+ projects.
+
+## Two Tiers
+
+### Core (every project)
+The `core/` directory describes the practices that run universally:
+- **Document hierarchy** — CLAUDE.md / SESSION.md / CONTEXT.md / IDEA.md
+- **Superpowers plugin** — The workflow engine (brainstorming, TDD, debugging, verification)
+- **Memory system** — Persistent feedback and project memories across sessions
+- **Backup before edit** — .backup/ directory before any modification
+- **Commit & push** — Every change, immediately, conventional commits
+- **Feedback behaviors** — Learned corrections and confirmed approaches
+
+### Advanced (complex projects only)
+The `rules/` directory contains `.claude/rules/` files for projects that need explicit governance beyond what the core provides.
 
 ## Structure
 
 | Directory | Purpose |
 |-----------|---------|
-| `rules/` | Core behavior rules (copy to `.claude/rules/`) |
+| `core/` | Universal practices (every project) |
+| `rules/` | Advanced governance rules (copy to `.claude/rules/`) |
 | `templates/` | File templates for bootstrapping new projects |
 | `hooks/` | Claude Code hooks (pre-push secret scanning) |
 | `settings/` | Example Claude Code configuration |
@@ -20,6 +35,6 @@ A collection of rules, templates, hooks, and methodology guides for working with
 ## Conventions
 
 - Conventional commits: `feat:`, `fix:`, `docs:`, `refactor:`, `test:`, `chore:`
-- All rules are self-contained markdown files with no external dependencies
+- All files are self-contained markdown with no external dependencies
 - Templates use `<placeholder>` syntax for values the user fills in
 - No credentials, IPs, or personal information anywhere in this repo