Initial TTRPG character meta-builder with visual sheet editor.

Offline Electron app seeds 10 system presets, supports create-from-scratch designer with palette/drag/resize/bricks, and exports .ttrpg-system.json for the player.

Co-authored-by: Cursor <cursoragent@cursor.com>

docs/adr/001-core.md

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+# ADR-001: Stack and storage
+
+## Decision
+
+Electron + React + TypeScript + Vite; SQLite with JSON documents for systems/characters; portable `app/shared` contract for future TTRPG Player + mobile.
+
+## Rationale
+
+Matches TTRPG Player packaging targets; offline-first; no Postgres.
+
+# ADR-002: Formula DSL
+
+## Decision
+
+Custom minimal expression language (`floor`, `ceil`, `round`, `min`, `max`, `clamp`, arithmetic, `attr.*` / `skill.*` / `resource.*` / `derived.*`).
+
+## Rationale
+
+Same evaluator can be copied into the player; explicit rounding; no heavy CEL/JSONata dependency.
+
+# ADR-003: Schema freeze via snapshotHash
+
+## Decision
+
+Player binds store `snapshotHash` (content-addressed) rather than inline full schema per character.
+
+## Rationale
+
+Implements freeze-on-bind without bloating `players.json`.
+
+# ADR-004: Spells from dnd.su
+
+## Decision
+
+Provide an import pipeline for PHB-labelled spells from dnd.su at product owner request, with README/IP disclaimer. Prefer SRD stubs in default presets.
+
+## Rationale
+
+Owner requested PHB coverage; redistribution risk acknowledged.

docs/testing.md

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+# Testing
+
+## Layers
+
+- **Unit** (`tsx --test`): `app/shared/*` — formula, derived, creation, snapshot, system validate
+- **Integration**: SQLite store (builder), GameSystemsStore (player)
+- **E2E** (Playwright Electron): functional asserts — not smoke-only (see plan)
+
+## Commands
+
+```bash
+# builder
+npm test
+npm run test:e2e   # when e2e suite is added
+
+# player (meta_builder)
+npx tsx --test app/main/gameSystems/gameSystemsStore.test.ts
+npx tsx --test app/shared/characterSheet/core.test.ts
+```
+
+## Preset smoke
+
+```bash
+node scripts/preset-smoke.mjs
+```
+
+Validates every `presets/*.json` (except samples) via `validateSystemDefinition` + sample derived compute.