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/setup/SKILL.md

@@ -213,19 +213,19 @@ Channels where the agent gets its own identity (name and avatar) are marked as r
 
 Invoke the matching skill:
 
-- **Discord:** Invoke `/add-discord-v2`
-- **Slack:** Invoke `/add-slack-v2`
-- **Telegram:** Invoke `/add-telegram-v2`
-- **GitHub:** Invoke `/add-github-v2`
-- **Linear:** Invoke `/add-linear-v2`
-- **Microsoft Teams:** Invoke `/add-teams-v2`
-- **Google Chat:** Invoke `/add-gchat-v2`
-- **WhatsApp Cloud API:** Invoke `/add-whatsapp-cloud-v2`
+- **Discord:** Invoke `/add-discord`
+- **Slack:** Invoke `/add-slack`
+- **Telegram:** Invoke `/add-telegram`
+- **GitHub:** Invoke `/add-github`
+- **Linear:** Invoke `/add-linear`
+- **Microsoft Teams:** Invoke `/add-teams`
+- **Google Chat:** Invoke `/add-gchat`
+- **WhatsApp Cloud API:** Invoke `/add-whatsapp-cloud`
 - **WhatsApp Baileys:** Invoke `/add-whatsapp`
-- **Resend:** Invoke `/add-resend-v2`
-- **Matrix:** Invoke `/add-matrix-v2`
-- **Webex:** Invoke `/add-webex-v2`
-- **iMessage:** Invoke `/add-imessage-v2`
+- **Resend:** Invoke `/add-resend`
+- **Matrix:** Invoke `/add-matrix`
+- **Webex:** Invoke `/add-webex`
+- **iMessage:** Invoke `/add-imessage`
 
 The skill will:
 1. Install the Chat SDK adapter package