feat(agents): implement dynamic Sisyphus prompt system with agent metadata

Introduce a new dynamic prompt generation system for Sisyphus orchestrator
that leverages agent metadata for intelligent delegation. This revives the
dynamic-sisyphus-agent-prompt branch with comprehensive refactoring.

Changes:
- Add AgentPromptMetadata, AgentCategory, AgentCost, DelegationTrigger types
- Create sisyphus-prompt-builder with dynamic prompt generation logic
- Add AGENT_PROMPT_METADATA exports to all agent modules (oracle, librarian,
  explore, frontend-ui-ux-engineer, document-writer, multimodal-looker)
- Refactor sisyphus.ts to use buildDynamicSisyphusPrompt()
- Add AvailableAgent type export for type safety

This enables Sisyphus to make intelligent agent selection decisions based on
agent capabilities, costs, and delegation triggers, improving orchestration
efficiency.

🤖 Generated with assistance of OhMyOpenCode
(https://github.com/code-yeongyu/oh-my-opencode)

src/agents/types.ts

@@ -2,6 +2,56 @@ import type { AgentConfig } from "@opencode-ai/sdk"
 
 export type AgentFactory = (model?: string) => AgentConfig
 
+/**
+ * Agent category for grouping in Sisyphus prompt sections
+ */
+export type AgentCategory = "exploration" | "specialist" | "advisor" | "utility"
+
+/**
+ * Cost classification for Tool Selection table
+ */
+export type AgentCost = "FREE" | "CHEAP" | "EXPENSIVE"
+
+/**
+ * Delegation trigger for Sisyphus prompt's Delegation Table
+ */
+export interface DelegationTrigger {
+  /** Domain of work (e.g., "Frontend UI/UX") */
+  domain: string
+  /** When to delegate (e.g., "Visual changes only...") */
+  trigger: string
+}
+
+/**
+ * Metadata for generating Sisyphus prompt sections dynamically
+ * This allows adding/removing agents without manually updating the Sisyphus prompt
+ */
+export interface AgentPromptMetadata {
+  /** Category for grouping in prompt sections */
+  category: AgentCategory
+
+  /** Cost classification for Tool Selection table */
+  cost: AgentCost
+
+  /** Domain triggers for Delegation Table */
+  triggers: DelegationTrigger[]
+
+  /** When to use this agent (for detailed sections) */
+  useWhen?: string[]
+
+  /** When NOT to use this agent */
+  avoidWhen?: string[]
+
+  /** Optional dedicated prompt section (markdown) - for agents like Oracle that have special sections */
+  dedicatedSection?: string
+
+  /** Nickname/alias used in prompt (e.g., "Oracle" instead of "oracle") */
+  promptAlias?: string
+
+  /** Key triggers that should appear in Phase 0 (e.g., "External library mentioned → fire librarian") */
+  keyTrigger?: string
+}
+
 export function isGptModel(model: string): boolean {
   return model.startsWith("openai/") || model.startsWith("github-copilot/gpt-")
 }