[codex] map SecondBrain to Notion project

[saagpatel]

What

Adds the SecondBrain Local Portfolio page ID to config/notion-project-map.json.

Why

A fresh BridgeDB SHIPPED row for SecondBrain surfaced as actionable because the registry knew SecondBrain as supp:SecondBrain but did not have its Notion Local Project page ID. Live Notion query found the exact Local Portfolio row at /Users/d/Documents/SecondBrain, so this should be a registry repair rather than a no-target disposition.

Review Of What Was Built

• Maps SecondBrain to Local Portfolio page 362c21f1-caf0-8147-8bbf-fa0fd3ae1480.
• Keeps the PR scoped to config/notion-project-map.json only.
• Leaves unrelated local portfolio-catalog.yaml residue untouched.

Cleanup Review

No removals. This prevents a real shipped event from being parked as no_durable_target when a live Notion target exists.

Verification Summary

• Live Notion Local Portfolio exact query found SecondBrain with URL https://app.notion.com/362c21f1caf081478bbffa0fd3ae1480, status Shipped, local path /Users/d/Documents/SecondBrain.
• Scratch JSON validation passed after adding the mapping.
• Scratch registry validation passed: supp:SecondBrain.notion_local_page_id resolves to 362c21f1-caf0-8147-8bbf-fa0fd3ae1480 and resolve("SecondBrain") returns supp:SecondBrain.

Shipped Summary

This branch makes fresh SecondBrain BridgeDB shipped rows eligible for receipt-backed Notion sync through canonical registry routing.

Next Phase

After merge, rerun bridge sync for shipped rows so activity 5391 writes a real Build Log receipt instead of staying actionable.

Remaining Roadmap

• Keep true no-target rows dispositioned until their canonical project registry or Notion page mapping is repaired.
• Continue using live Notion exact checks before classifying newly actionable shipped rows.