docs: complete and improve ReMe documentation

**Background**

ReMe has English and Chinese guides for its core file-native memory workflows, but the documentation should be completed and kept aligned with the current code, public schemas, CLI, default configuration, integrations, and operational behavior. The documentation must clearly separate the README-supporting pages in this repository from the deployed website owned by `agentscope-ai/docs`.

**Changes**
- Audit existing English and Chinese documentation against the current implementation, public Pydantic schemas, CLI help, and `reme/config/default.yaml`
- Complete the installation and quick-start paths for local CLI, service, HTTP, MCP, and Python SDK usage
- Clarify the file-native workspace model, source-of-truth boundaries, generated indexes, session state, and rebuild and recovery workflows
- Document the complete memory lifecycle: ingestion, auto memory, resources, indexing, retrieval, linking, consolidation, and proactive topics
- Add a practical configuration reference covering components, jobs, credentials, workspace paths, service boundaries, and environment variables
- Document supported AgentScope, Claude Code, QwenPaw, OpenClaw, Hermes Agent, and Codex integration paths as implementations become available
- Add benchmark setup and reproducibility guidance for LoCoMo, LongMemEval, BEAM, and future personal or proactive evaluations
- Improve troubleshooting, observability, privacy, security, backup, migration, and failure-recovery guidance
- Keep English and Chinese pages structurally aligned and preserve README-linked paths under `docs/en`, `docs/zh`, and `docs/figure`
- Validate commands, examples, relative links, images, and configuration snippets through lightweight automated documentation checks
- Publish website-owned content and navigation changes in `agentscope-ai/docs` under the appropriate `reme//` path instead of adding website build or deployment configuration here

**Acceptance Criteria**

- Every documented workflow is reproducible against a supported ReMe version
- Public commands, configuration keys, schemas, and examples match current behavior
- English and Chinese navigation cover the same stable user-facing topics
- Repository-local and deployed-documentation ownership is explicit
- Documentation checks detect broken links and stale executable examples where practical