docs: add code style (120 char lines, concise logging) and config pattern

Skills document env vars in SKILL.md instead of patching config.ts.
Prettier printWidth 120 to keep log calls and signatures on one line.
Thin logging wrapper for one-line structured log calls.

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

docs/v2-architecture-draft.md

@@ -554,10 +554,9 @@ registerChannel('gmail', {
 
 The container runner reads registered mounts from the channel registry — no need to edit `container-runner.ts`.
 
-**Config pattern:** Instead of a central `config.ts` that every skill edits:
+**Config pattern:** Skills don't patch `config.ts` or `.env.example`. Skill-specific env vars are documented in the skill's SKILL.md — the setup process reads those instructions. Each module reads its own env vars directly:
 
 ```typescript
-// Each module reads its own config
 // channels/discord.ts
 const DISCORD_TOKEN = process.env.DISCORD_BOT_TOKEN;
 
@@ -567,6 +566,18 @@ const GMAIL_CREDS = process.env.GMAIL_CREDENTIALS_PATH;
 
 Shared config (DATA_DIR, TIMEZONE, MAX_CONCURRENT_CONTAINERS) stays in `config.ts`. Channel/skill-specific config stays in the module that uses it.
 
+### Code Style
+
+**Line width: 120 characters.** v1 uses the prettier default of 80, which breaks simple log calls and function signatures across 3-4 lines. v2 uses 120 — most statements fit on one line without sacrificing readability.
+
+**Concise logging.** v1 has 138 log calls, many spanning 3-4 lines due to pino's structured API + 80-char wrapping. v2 uses a thin wrapper so every log call is one line:
+
+```typescript
+log.info('IPC message sent', { chatJid, sourceGroup });
+log.warn('Unauthorized IPC attempt', { chatJid });
+log.error('Error processing', { file, err });
+```
+
 ### DB File Structure
 
 v1's DB is one 750-line file with all tables, all CRUD functions, and all migrations inline. v2 splits by entity: