[feature] 新增基于规则的 provider

[fatsheep2]

Description

新增运行时模板 Provider 的核心解释器能力，用规则表达导入逻辑，并补充模板 Provider 的使用文档与示例配置。

本 PR 未关联具体 issue。

Motivation and Context

当前各 Provider 的导入逻辑分散在专用代码里，维护和扩展新账单格式成本较高。

本 PR 将可复用的解析、规则匹配、变量、posting 生成等能力收敛到运行时模板 Provider 中。后续模板可以在独立模板仓库维护，DEG 主库只保留解释器、CLI 和文档入口，减少主库与模板数据的耦合。

Dependencies

无新增运行时外部依赖。

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How has this been tested?

已在本地运行以下测试：

• Test A: GOCACHE=/private/tmp/go-build-cache GOPATH=/private/tmp/go-path make check-format
• Test B: GOCACHE=/private/tmp/go-build-cache GOPATH=/private/tmp/go-path go test ./pkg/cmd ./pkg/importer ./pkg/compiler/...
• Test C: GOCACHE=/private/tmp/go-build-cache GOPATH=/private/tmp/go-path make test
• Test D: GOCACHE=/private/tmp/go-build-cache GOPATH=/private/tmp/go-path GOLANGCI_LINT_CACHE=/private/tmp/golangci-lint-cache PATH=/private/tmp/go-path/bin:$PATH golangci-lint run --timeout=5m

测试配置：macOS，本地 Go cache/GOPATH 指向 /private/tmp。

Is this change properly documented?

是。已补充模板 Provider 文档、配置说明和示例。

[fatsheep2]

@gaocegege @Triple-Z @deb-sig/generator-dev need review
这次把jieba的拆成另一个pr了,仅包含必要更改

[Triple-Z]

LGTM

[Triple-Z]

This feature can be considered as v3 core feature.