chore(road-editor): plan direct-edit task tree and add client test infra

Planning: parent design.md becomes the single authoritative contract
(constraint model with 6 kinds, handle manifest, coordinate/unit
layering, preview sequencing, storage layout and lazy migration, area
config snapshot, API contract). Work is split into four independently
verifiable child tasks with per-step gates and rollback points.

Test infra: pin vitest 4.1.11, add test:client:unit for client pure
logic, extend prettier globs to root *.ts so vitest.config.ts is checked.

Add .gitignore: the repo had none, so inputs/, outputs/, workbench-data/
and the client build output were untracked rather than ignored.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.trellis/tasks/08-26-direct-edit-solver-api/implement.jsonl

@@ -0,0 +1,7 @@
+{"file": ".trellis/tasks/08-26-direct-manipulation-road-editor/design.md", "reason": "父任务权威合约：约束模型、handle manifest 字段、坐标分层、预览时序、不变量、API 合约"}
+{"file": ".trellis/tasks/08-26-direct-manipulation-road-editor/research/joint-solver.md", "reason": "求解阶段插入点、图层依赖链顺序与约束不变量的完整来源"}
+{"file": ".trellis/tasks/08-26-direct-manipulation-road-editor/research/current-system.md", "reason": "compileGeometry 现有输入输出、feature 回链字段与 v1 overrides 复用点"}
+{"file": ".trellis/tasks/08-26-direct-manipulation-road-editor/research/data-model-options.md", "reason": "分层求解规则与重放匹配策略的推导过程"}
+{"file": ".trellis/tasks/08-26-direct-manipulation-road-editor/research/junction-tools.md", "reason": "junction reserve 所有权划分与 approach 约束优先级的依据"}
+{"file": ".trellis/spec/guides/code-reuse-thinking-guide.md", "reason": "米制换算必须复用 src/geometry/lane-geometry.js，禁止新增第二套换算函数"}
+{"file": ".trellis/spec/guides/cross-layer-thinking-guide.md", "reason": "新增 API 载荷与 manifest 字段跨编译器/服务端/客户端三层"}