v0.5.0

Major rework of the system prompt system, JSON hooks, multi-result tool support, and message origin tracking.

Breaking

• chat.system(content) → chat.system().child('general').prompt('id').setContent(content)
• ChatJSON.systemMessage → ChatJSON.systemPrompt
• ChatMessage.origin is now required (enum: User/Model/Hook/Tool/System)
• ChatInterface.addAll() removed (method still exists on Chat class)
• Chat.clear() now clears message hook listeners by default (was: hooks survived)
• ChunkStream.clear() now clears chunk listeners by default (was: listeners survived)
• Tool.execute() returns ToolResult[]
• ToolSuite.executeTool() returns arrays, never throws (returns error result)
• ToolPackage is abstract class (was interface); dispose() removed
• ChatService.needsResend() removed; use setNeedsResend(), send() loops automatically
• MessageQueue.system() and .addAll() removed

Features

• Composable system prompts via PromptContainer/Prompt tree
• ChatMessageOrigin on every message; HookMessageWriter interface
• ResultBuilder for multi-result tool chains
• JsonHookRegistry: load .json hooks from a directory (chat/stream/tool targets)
• ToolPackage.tutorial() auto-populates the system prompt
• ChatService.init() (eager loading), .clear() (full reset), .resetTutorials()
• ChunkStream.summary() / .clearSummaries()
• clear(retainHooks?) on Chat, ChunkStream, ToolSuite
• systemPromptDir with auto-created default .md files on first access
• LLM_CHAT_HOOKS_DIR and LLM_CHAT_SYSTEM_PROMPT_DIR env vars
• envOptionalString() helper for optional env var config
• Coverage thresholds raised to 100%

Full Changelog: v0.4.0...v0.5.0