Remove legacy infrastructure, keep only shared rule contracts

Deleted: demo app, designsync/exports bundle system, bible meta-docs,
theme CSS, scaffolds, examples, empty pattern placeholders, go.mod,
CHANGELOG, VERSIONING

Kept: kit/patterns/*/contract.md (all engineering rules),
kit/ai/claude/CLAUDE.template.md, CLAUDE.md, AGENTS.md, README.md

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

kit/ai/codex/AGENTS.template.md

@@ -1,10 +0,0 @@
-# {{ .project_name }} — Agent Instructions
-
-Read and follow `bible/README.md` as the architecture source of truth.
-
-## Rules
-
-- Keep architecture documentation in English.
-- Update Bible docs in the same change set as architecture/code contract changes.
-- Keep README and agent docs minimal; avoid duplicating Bible architecture content.
-

kit/ai/shared/ARCH_DOC_POLICY.md

@@ -1,11 +0,0 @@
-# Architecture Documentation Policy
-
-This project uses a Bible-style architecture documentation folder as the single source of truth.
-
-## Mandatory Rules
-
-- Record architecture decisions before or together with implementation.
-- Use English for architecture documentation.
-- Remove or update obsolete architectural guidance in the same change.
-- Keep non-Bible docs concise and reference the Bible instead of duplicating it.
-