宜博 / lemongraph

A merged graph's one run genuinely spans several org_nodes now (Planner/
Coder/Validator all append their own nodes into the SAME run) -- a single
run-level org_node column was never accurate once Phase 2b/2c landed, and
real per-node ownership already lives in work_node_execution.subagent_type.

Schema: work_graph_run.org_node column removed; ux_work_graph_run_active
narrowed from UNIQUE(task_id, org_node) to UNIQUE(task_id) WHERE status
NOT IN ('done', 'failed') -- 'blocked' now counts as active on purpose,
since resuming a blocked run always appends into the same row rather than
inserting a fresh one. New migrate_drop_work_graph_run_org_node() handles
already-populated databases, wired into backend_server.py's startup path.

Call sites updated: work_graph_plan.py/work_graph_fork.py/
root_cause_trace.py's INSERTs; work_graph_run_query.py/task_query.py now
return "org_nodes_involved" (derived from work_node_execution.subagent_type)
instead of the removed single-value "org_node"; frontend/app.js's org-strip
and run-list rendering updated to the list-based shape.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

c_artifact_get 在机器可读的 sdd-mvcp-contract.json 里其实定义过
（GET /api/artifacts/:artifact_id），只是 03-C 正文一直没写出来，已订正
补全。c_artifact_list 连 MVCP JSON 里都没有 operation 定义，纯粹是
v_artifact_browser 自己的过滤字段倒逼出来的缺口，跟 U-025 补 c_task_list
是同一类问题。

新增 src/artifact_query.py：list_artifacts() 返回裸数组（跟已有的
list_tasks() 保持同款风格）；get_artifact() 把血缘链（按
depends_on_artifact_ids 往回走，只走第一个依赖——这条流水线的实际产出
只有线性 BRD→PRD→SDD 链）和文件内容（artifact 表本身没有 content 列，
走 project.target_folder_path + artifact.file_path 现读磁盘）一起返回，
预览面板一次请求就够。

前端预览统一用 <pre> 纯文本展示，不做 Markdown 渲染/代码高亮——02-V
原文想要那个效果，但需要引入第一个前端第三方库，跟这个控制台一贯的纯
vanilla JS、无构建步骤做法冲突，是有意简化。顺手给 index.html 常驻导航
栏加上了"产物"链接。

真实服务器验证过三级血缘链（BRD→PRD→SDD）返回顺序正确。

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>