Story 50: Unified Current Work Directory

- Move current/ to .story_kit/current/ (out of stories/)
- Type-aware routing for bugs, spikes, stories
- close_bug_to_archive() for bug lifecycle
- All path references updated across agents.rs, workflow.rs, mcp.rs

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.story_kit/stories/current/50_unified_current_work_directory.md

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+---
+name: Unified Current Work Directory
+test_plan: approved
+---
+
+# Story 50: Unified Current Work Directory
+
+## User Story
+
+As a developer, I want a single `.story_kit/current/` directory (outside of `stories/`) that holds whatever work items agents are actively working on — stories, bugs, or spikes — so I can always see at a glance what coders are doing.
+
+## Acceptance Criteria
+
+- [ ] New top-level `.story_kit/current/` directory replaces `.story_kit/stories/current/`
+- [ ] `start_agent` moves work items into `.story_kit/current/` regardless of type (story, bug, spike)
+- [ ] `accept_story` moves from `.story_kit/current/` to `.story_kit/stories/archived/`
+- [ ] `close_bug` moves from `.story_kit/current/` to `.story_kit/bugs/archive/`
+- [ ] All existing references to `.story_kit/stories/current/` are updated (server code, tests, MCP tools)
+- [ ] Migrate any files currently in `.story_kit/stories/current/` to `.story_kit/current/`
+- [ ] Auto-commits use deterministic messages for all moves
+- [ ] Integration test: full story lifecycle — create_story → start_agent (moves to current/) → check_criterion → accept_story (moves to stories/archived/)
+- [ ] Integration test: full bug lifecycle — create_bug → start_agent (moves to current/) → close_bug (moves to bugs/archive/)
+- [ ] Integration test: full spike lifecycle — start_agent (moves to current/) → completion (moves back or archives)
+- [ ] All deterministic MCP tools (`create_story`, `accept_story`, `close_bug`, `check_criterion`, `set_test_plan`, `start_agent`) resolve paths correctly against the new directory layout
+- [ ] `list_current` MCP tool (or update `list_agents`) shows all items in `.story_kit/current/` with their type (story/bug/spike)
+- [ ] All agent prompts in `.story_kit/project.toml` (supervisor, coders) updated to reference correct directory paths and workflow steps
+
+## Out of Scope
+
+- UI changes to display current work items