docs: add per-module READMEs with architecture and DB schemas

Each module now has a README.md documenting commands, architecture,
and database schema (KV keys, JSON structure, field descriptions).
Trading README enhanced with full schemas for user portfolio and
price cache objects.

src/modules/loldle/README.md

@@ -0,0 +1,20 @@
+# Loldle Module
+
+League of Legends guessing game — currently a stub proving the plugin system.
+
+## Commands
+
+| Command | Visibility | Description |
+|---------|-----------|-------------|
+| `/loldle` | public | Start a loldle game (stub) |
+| `/lstats` | protected | Show loldle stats (stub) |
+| `/ggwp` | private | Easter egg — "gg well played" |
+
+## Architecture
+
+- All commands return stub responses. Real game logic is not yet implemented.
+- No `init()` hook — this module does not use KV storage yet.
+
+## Database
+
+**No KV usage currently.** When game logic is implemented, it will use KV namespace prefix `loldle:`.

src/modules/misc/README.md

@@ -0,0 +1,35 @@
+# Misc Module
+
+Health check and DB demonstration. Exercises all three visibility levels.
+
+## Commands
+
+| Command | Visibility | Description |
+|---------|-----------|-------------|
+| `/ping` | public | Health check — replies "pong" and records timestamp |
+| `/mstats` | protected | Shows last `/ping` timestamp |
+| `/fortytwo` | private | Easter egg — replies "The answer." |
+
+## Architecture
+
+- `/ping` writes a timestamp to KV on every call (best-effort — KV failure doesn't block the reply).
+- `/mstats` reads the last ping timestamp and formats it as ISO string.
+- `/fortytwo` is a hidden command demonstrating private visibility.
+
+## Database
+
+KV namespace prefix: `misc:`
+
+| Key | Type | Description | Example |
+|-----|------|-------------|---------|
+| `last_ping` | JSON | Timestamp of the most recent `/ping` call | `{ "at": 1713100000000 }` |
+
+### Schema: `last_ping`
+
+```json
+{
+  "at": 1713100000000
+}
+```
+
+- `at` — Unix epoch milliseconds (`Date.now()`)

src/modules/trading/README.md

@@ -28,16 +28,48 @@ Paper-trading system where each Telegram user manages a virtual portfolio.
 
 Currencies: VND, USD.
 
-## Data Model
+## Database
 
-Per-user portfolio stored as a single KV object at key `user:<telegramId>`:
+KV namespace prefix: `trading:`
 
-```js
-{ currency: { VND, USD }, stock: {}, crypto: {}, others: {}, totalvnd: 0 }
+| Key | Type | Description |
+|-----|------|-------------|
+| `user:<telegramId>` | JSON | Per-user portfolio (balances + holdings) |
+| `prices:latest` | JSON | Cached merged prices from all APIs |
+
+### Schema: `user:<telegramId>`
+
+```json
+{
+  "currency": { "VND": 5000000, "USD": 100 },
+  "stock": { "TCB": 10, "FPT": 5 },
+  "crypto": { "BTC": 0.005, "ETH": 1.2 },
+  "others": { "GOLD": 0.1 },
+  "totalvnd": 10000000
+}
 ```
 
-- `totalvnd` tracks cumulative VND value of all top-ups (cost basis for P&L)
+- `currency` — fiat balances (VND, USD)
+- `stock` / `crypto` / `others` — asset quantities keyed by symbol
+- `totalvnd` — cumulative VND value of all top-ups (cost basis for P&L)
 - VND is the sole settlement currency — buy/sell deducts/adds VND
+- Empty categories are `{}`, not absent — migration-safe loading fills missing keys
+
+### Schema: `prices:latest`
+
+```json
+{
+  "ts": 1713100000000,
+  "crypto": { "BTC": 1500000000, "ETH": 50000000, "SOL": 3000000 },
+  "stock": { "TCB": 25000, "VPB": 18000, "FPT": 120000, "VNM": 70000, "HPG": 28000 },
+  "forex": { "USD": 25400 },
+  "others": { "GOLD": 72000000 }
+}
+```
+
+- `ts` — Unix epoch milliseconds of last fetch
+- All prices in VND per unit
+- Cache TTL: 60 seconds (stale fallback up to 5 minutes)
 
 ## Price Sources
 

src/modules/util/README.md

@@ -0,0 +1,20 @@
+# Util Module
+
+Core bot utilities — informational commands that read framework metadata.
+
+## Commands
+
+| Command | Visibility | Description |
+|---------|-----------|-------------|
+| `/info` | public | Echoes chat id, thread id, sender id (debug helper) |
+| `/help` | public | Renders all public + protected commands grouped by module |
+
+## Architecture
+
+- `/help` is a pure renderer over `getCurrentRegistry()` — it reads the registry's command maps and formats them as Telegram HTML. Modules with zero visible commands are omitted. Private commands are always excluded.
+- `/info` reads grammY context fields (`ctx.chat.id`, `ctx.message.message_thread_id`, `ctx.from.id`). No external state.
+- HTML injection is prevented via `escapeHtml()` on all user-influenced strings.
+
+## Database
+
+**No KV usage.** This module has no `init()` hook and does not store any data.

src/modules/wordle/README.md

@@ -0,0 +1,35 @@
+# Wordle Module
+
+Word guessing game — currently a stub proving the plugin system.
+
+## Commands
+
+| Command | Visibility | Description |
+|---------|-----------|-------------|
+| `/wordle` | public | Start a wordle game (stub) |
+| `/wstats` | protected | Show wordle stats |
+| `/konami` | private | Easter egg — "secret wordle mode" |
+
+## Architecture
+
+- All commands return stub responses. Real game logic is not yet implemented.
+- `/wstats` reads a `stats` key from KV (returns 0 games played when empty).
+- Module captures `db` in closure via `init()` for future game state persistence.
+
+## Database
+
+KV namespace prefix: `wordle:`
+
+| Key | Type | Description | Example |
+|-----|------|-------------|---------|
+| `stats` | JSON | Aggregate game statistics (planned) | `{ "gamesPlayed": 0 }` |
+
+### Schema: `stats` (planned)
+
+```json
+{
+  "gamesPlayed": 0
+}
+```
+
+No data is currently written — the module only reads this key defensively.