fix: Simplify propose_content tool and add allocation perspective

[bokelley]

Summary

• Add new perspective article: "Agentic Advertising is for Allocation"
• Fix URL-encoded Slack interactive payload parsing in Addie /events endpoint
• Add logging for Addie tool errors and error-like results
• Simplify propose_content tool schema by removing confusing "personal" vs "committee" distinction

Key Changes

propose_content Tool Simplification

The tool schema previously had a confusing nested collection object:

{
  "collection": {
    "type": "personal" | "committee",
    "committee_slug": "..."
  }
}

This was misleading because:

1. There's no "personal" collection - migration 153 moved all personal content to the editorial working group
2. The "personal" option was just syntactic sugar for committee_slug: 'editorial'

New schema:

{
  "committee_slug": "editorial"  // defaults to editorial (Perspectives) if omitted
}

The handler maintains backward compatibility with the legacy format and validates that committee_slug is provided when using collection.type='committee'.

Other Fixes

• Slack payload parsing: Handle URL-encoded payload=... format for interactive components
• Error logging: Log tool exceptions (ERROR) and error-like results (WARN) for debugging

Test plan

• All existing tests pass
• TypeScript type checking passes
• Code review completed and suggestions addressed

🤖 Generated with Claude Code