Add dotclaude configuration files

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

CLAUDE.md

@@ -0,0 +1,49 @@
+# Project Instructions
+
+> REPLACE: Customize this file for your project. Delete sections that don't apply — every line costs tokens. Code style lives in .claude/rules/code-quality.md — don't duplicate here. Run `/setupdotclaude` to auto-customize, or edit manually and delete all `> REPLACE:` blocks when done.
+
+## Commands
+
+```bash
+# Build
+npm run build            # or: cargo build, go build ./..., make build
+
+# Test
+npm test                 # run full suite
+npm test -- path/to/file # run single test file
+
+# Lint & Format
+npm run lint             # check style
+npm run lint:fix         # auto-fix style
+npm run typecheck        # type checking
+
+# Dev
+npm run dev              # start dev server
+```
+
+## Architecture
+
+> REPLACE: Describe non-obvious architectural decisions. Don't list files — Claude can explore.
+
+- `src/` — application source
+- `src/api/` — REST endpoints (versioned: `/v1/`)
+- `src/services/` — business logic (no direct DB access from controllers)
+- `src/models/` — data models and types
+
+## Key Decisions
+
+> REPLACE: Record WHY non-obvious choices were made. This is the most valuable section. Examples: "Auth tokens in httpOnly cookies because XSS risk", "Billing is a separate module for audit independence".
+
+## Domain Knowledge
+
+> REPLACE: Terms, abbreviations, or concepts that aren't obvious from the code. Example: "SKU" = Stock Keeping Unit, the unique product identifier from our warehouse system.
+
+## Workflow
+
+- Run typecheck after making a series of code changes
+- Prefer fixing the root cause over adding workarounds
+- When unsure about approach, use plan mode (`Shift+Tab`) before coding
+
+## Don'ts
+
+- Don't modify generated files (`*.gen.ts`, `*.generated.*`)