docs: add stats dashboard design docs, plans, and knowledge base

- Stats dashboard redesign design and implementation plans
- Episode detail and Anki card link design
- Internal knowledge base restructure
- Backlog tasks for testing, verification, and occurrence tracking

docs/architecture/README.md

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+<!-- read_when: changing runtime wiring, moving code across layers, or trying to find ownership -->
+
+# Architecture Map
+
+Status: active
+Last verified: 2026-03-13
+Owner: Kyle Yasuda
+Read when: runtime ownership, composition boundaries, or layering questions
+
+SubMiner runs as three cooperating runtimes:
+
+- Electron desktop app in `src/`
+- Launcher CLI in `launcher/`
+- mpv Lua plugin in `plugin/subminer/`
+
+The desktop app keeps `src/main.ts` as composition root and pushes behavior into small runtime/domain modules.
+
+## Read Next
+
+- [Domains](./domains.md) - who owns what
+- [Layering](./layering.md) - how modules should depend on each other
+- Public contributor summary: [`docs-site/architecture.md`](../../docs-site/architecture.md)
+
+## Current Shape
+
+- `src/main/` owns composition, runtime setup, IPC wiring, and app lifecycle adapters.
+- `src/core/services/` owns focused runtime services plus pure or side-effect-bounded logic.
+- `src/renderer/` owns overlay rendering and input behavior.
+- `src/config/` owns config definitions, defaults, loading, and resolution.
+- `src/main/runtime/composers/` owns larger domain compositions.
+
+## Architecture Intent
+
+- Small units, explicit boundaries
+- Composition over monoliths
+- Pure helpers where possible
+- Stable user behavior while internals evolve