Prepare 0.3.0: durable crash recovery, runtime fixes and release validation

[wangcch]

This prepares 0.3.0 with durable-task recovery, runtime improvements and release tooling updates.

• Add active durable-task crash recovery, execution fencing, admission and signal idempotency keys, and retained-result inspection and cleanup.
• Fix HTTP deadlines and shutdown draining, byte preservation, URL handling and stream backpressure; extend Streams, encoding and Response APIs.
• Cache durable export metadata and wake the local scheduler after signal commits.
• Improve project initialization, type synchronization and structured diagnostics; synchronize English and Chinese documentation.
• Align versions to 0.3.0 and maintain a changelog with automatic release-note validation and extraction.

Upgrade notes

• Opening a store migrates durable log v1/v2 to v3. Stop all old writers and back up the complete store first; rollback requires the pre-upgrade snapshot.
• Legacy orphan tasks without wakeup or execution records are not automatically recovered. External writes still require provider idempotency or reconciliation.
• Application outboxes do not share a transaction with the runtime database; admission retries across deployments require the original bundle. Cleanup removes idempotency records, so retention must exceed the retry horizon.

Local Rust tests, live database tests, all 24 Release crash gates and packaging checks passed; the full release matrix is validated separately.

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本次准备 0.3.0，完善持久任务恢复、运行时行为及发布流程。

• 支持活跃持久任务崩溃恢复、执行租约隔离、准入与信号幂等键，以及完成结果查询和清理。
• 修复 HTTP 截止时间与关闭排空、字节保真、URL 处理和流背压问题，扩展 Streams、编码及 Response API。
• 缓存 durable 导出元数据，信号提交后唤醒本地调度器。
• 改进项目初始化、类型同步和结构化诊断，同步中英文文档。
• 统一版本为 0.3.0，维护 changelog，并自动校验、提取 Release 说明。

升级注意

• Durable log v1/v2 在打开时迁移到 v3。升级前停止所有旧写入者并备份完整存储；回滚需要升级前快照。
• 缺少唤醒及执行记录的旧孤儿任务不会自动恢复。外部写入仍需提供方幂等或结果核对。
• 应用 outbox 不与运行时数据库共享事务；跨版本准入重试需使用原 bundle。清理会删除幂等记录，保留期应长于重试窗口。

本地 Rust 测试、真实数据库测试、24/24 Release 崩溃门禁及打包检查通过；完整发布矩阵另行验证。