Add harness coding docs for SoftBox (Go + Gio dual-build)

Initialize the full harness coding document set from the
harness_coding_docs template, customized for the SoftBox project:

- Vision, requirements, tech stack (modern Go 1.25 + Gio v0.10.1;
  Win7 legacy Go 1.20.14 + Gio v0.6.0), architecture, coding rules
- Protocol contracts (signed catalog, package protocol v1, Ed25519
  license, events, CLI) and Gio view structure
- Roadmap Phase 0-6 with 20 suggested tasks; T-001 (monorepo
  skeleton) filed and ready to claim
- Agent entry points (AGENTS.md, docs/00-ai-start-here.md),
  context manifest, governance scripts and tests
- Merge Go gitignore with harness rules; keep go.work tracked

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

.gitea/ISSUE_TEMPLATE/task.md

@@ -0,0 +1,36 @@
+---
+name: Agent task
+about: 创建与 docs/tasks/T-<编号>.md 一一对应的开发任务
+title: "[T-XXX] "
+ref: ""
+labels:
+  - kind/task
+---
+
+## 任务映射
+
+- task_id: `T-XXX`
+- task_file: `docs/tasks/T-XXX.md`
+- context_ref: `【领取时的默认分支提交 SHA】`
+- deps: `【T-编号列表或无】`
+- write_paths:
+  - `docs/tasks/T-XXX.md`
+  - `【允许修改的仓库相对路径】`
+
+## 问题与方案
+
+【链接任务文件对应章节；Issue 只写协调所需摘要，不复制整份规格。】
+
+## 验收入口
+
+【真实验证命令和可观察结果；长期证据回填到任务文件。】
+
+## 协作状态
+
+- expected_claim_branch: `claims/T-XXX`
+- work_branch: `【领取后填写】`
+- claimed_by: `【领取后填写非敏感 agent-id】`
+- lease_until: `【领取后填写 RFC 3339 时间】`
+
+领取必须遵循 `docs/gitea-collaboration.md` 的 dispatcher 串行分配与 claim 标记流程。不要在本 Issue 粘贴 Token、Authorization header 或私有配置。
+创建后先把 Issue 编号回填任务文件并合入默认分支，再按主要变更选择唯一 `type/docs` 或 `type/code`、一个 `priority/*` 和 `status/todo`。映射提交完成前不可领取。

.gitea/PULL_REQUEST_TEMPLATE.md

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+## 任务映射
+
+- Closes #【Issue 编号】
+- task_file: `docs/tasks/T-XXX.md`
+- context_ref: `【领取任务时的提交 SHA】`
+- claim_branch: `claims/T-XXX`
+- work_branch: `agent/【agent-id】/T-XXX`
+- write_paths:
+  - `docs/tasks/T-XXX.md`
+  - `【本 PR 允许修改的仓库相对路径】`
+
+## 变更摘要
+
+【改了什么，以及为什么符合任务方案。】
+
+## 验证证据
+
+| 命令 | 结果 |
+| --- | --- |
+| `【真实命令】` | 【通过 / 失败摘要】 |
+
+## 风险与回滚
+
+【已知风险、兼容性影响、回滚方法；没有则写“无”。】
+
+## 检查清单
+
+- [ ] 当前 PR 只对应一个任务 / Issue。
+- [ ] 变更未超出 `write_paths`，没有夹带无关修改。
+- [ ] 任务文件执行记录包含相同的验证证据。
+- [ ] 合并前任务文件 frontmatter 已为 `DONE`；`Closes` 自动关闭 Issue 不会制造假完成。
+- [ ] 未提交 Token、Authorization header、私有配置或实例地址。
+- [ ] Issue 已切换到唯一 `status/review`；合并后才标记 `status/done`。

.gitea/workflows/harness-governance.yml

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+name: Harness governance
+
+on:
+  push:
+  pull_request:
+
+permissions: read-all
+
+jobs:
+  validate:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+      - name: Validate templates and governance
+        run: |
+          python scripts/validate_agent_context.py
+          python -m unittest discover -s tests -p "test_*.py"
+          python scripts/validate_harness_governance.py