chore(release): bump agent-node 2.4.8-preview.0 → 2.4.8 — Method B Phase 2a preflight

Method B Phase 2 promote per Vincent telegram 7007 ("跑" trigger 09:51 BJT):
- Phase 2a (this commit): publish 2.4.8 to --tag preview (latest stays 2.4.7)
- Phase 2b (pending Lane A PASS GO from 通信龙): npm dist-tag add 2.4.8 latest
- Phase 2c: GH release v0.10.12 with Install vs Upgrade 分块

Ship content (cumulative from 4a63f3b + 875afe4):
- scenario 2 video gen artifact extractor (50 LOC surface path helper)
- scenario 1 ANET_GROK_TUI_FALLBACK env-var infra + _meta hint forward-compat (NO-OP today)

PINNED audit (per [[feedback_pinned_chain_bump_verify]] + [[feedback_pinned_version_npm_match_required]]):
- PINNED_SERVER_VERSION="0.8.4" matches commhub-server latest 0.8.4 ✓
- No PINNED_NODE_VERSION constant (line 2378 uses @Preview tag, auto-tracks)
- After Phase 2b: latest=2.4.8, preview=2.4.8 (single clean version on both tags)

Author-Agent: 通信工程马

Author: SmartFlowAITeam

agent-node/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@sleep2agi/agent-node",
-  "version": "2.4.8-preview.0",
+  "version": "2.4.8",
   "description": "AI Agent runtime for CommHub networks. Supports 4 runtimes: Claude Code CLI, Claude Agent SDK, Codex SDK, and Grok Build ACP.",
   "bin": {
     "agent-node": "dist/cli.js"