feat: Add Haiku-powered dynamic placeholder text

[gustafeden]

Summary

Generates witty placeholder text using Claude Haiku at startup, with a typing animation effect.

Stacked on PR #5 (feature/haiku-core-clean)

What's Included

New Files

• lib/modules/haiku/prompts/placeholder_prompt.dart - Prompt for generating creative placeholders

Modified Files

• lib/modules/agent_network/pages/networks_overview_page.dart - Haiku integration + typing animation

User-Visible Behavior

1. On startup, Haiku generates a witty 3-5 word placeholder
2. Text appears with typing animation effect
3. Falls back to static text if Haiku fails
4. Examples: "What are we breaking today?", "Got bugs?", "Your wish, my code..."

Test Plan

• Launch app, verify placeholder appears with typing animation
• Verify fallback works when Haiku unavailable

🤖 Generated with Claude Code