docs(skills): drop "v2" from skill content + src/index.ts log lines

Cleans up the prose-level v2 references that the rename commit didn't
touch. Skills now describe themselves and the codebase without "v2"
versioning language. /add-X-v2 cross-references in setup, init-first-agent,
and manage-channels updated to /add-X.

Runtime path identifiers (data/v2.db, data/v2-sessions/, container name
nanoclaw-v2) deliberately left as-is — renaming them breaks live installs
without commensurate benefit.

Verified: pnpm run build clean, 326 host tests pass.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.claude/skills/add-dashboard/SKILL.md

@@ -1,6 +1,6 @@
 ---
 name: add-dashboard
-description: Add a monitoring dashboard to NanoClaw v2. Installs @nanoco/nanoclaw-dashboard and a pusher that sends periodic JSON snapshots.
+description: Add a monitoring dashboard to NanoClaw. Installs @nanoco/nanoclaw-dashboard and a pusher that sends periodic JSON snapshots.
 ---
 
 # /add-dashboard — NanoClaw Dashboard
@@ -65,7 +65,7 @@ Add the `readEnvFile` import at the top if not already present:
 import { readEnvFile } from './env.js';
 ```
 
-Add after step 7 (OneCLI approval handler), before the `log.info('NanoClaw v2 running')` line:
+Add after step 7 (OneCLI approval handler), before the `log.info('NanoClaw running')` line:
 
 ```typescript
   // 8. Dashboard (optional)