docs: clarify the repository open-source scope

[Yangtze-Seventh]

Summary

Clarify that this repository contains EverMe's open-source client toolchain and Agent integrations, while the EverMe product, web application, and managed backend are separate. Keep the English and Chinese READMEs aligned with the capabilities currently shipped in the repository.

Changes

• Rename the README heading and opening copy to describe the CLI, MCP server, SDK, and Agent plugins precisely
• Add an explicit scope notice and clarify the Apache-2.0 license scope
• Remove product-only digital-twin marketing from the repository overview
• Sync the documented install commands and Agent support table with all 12 platforms registered by the current CLI
• Document the current Codex, Cursor, Devin, DeepSeek Harness, Kimi Code, Raven, and WorkBuddy integrations
• Remove the retired Gemini CLI entry and align the Chinese README with the English README
• Merge the latest upstream main, including the dependency security fixes from the 0.6.1 / evercli 0.32.0 sync

Test Plan

• cd cli && go build ./...
• cd cli && go vet ./...
• cd cli && go test -race -count=1 -timeout=5m ./...
• cd cli && go test -coverprofile=coverage.txt -covermode=atomic ./...
• cd plugins && npm test --workspaces --if-present
• cd plugins && npm audit --audit-level=moderate — 0 vulnerabilities
• Manifest parsing, README path checks, and parity checks for all 12 registered Agent installers
• GitHub Actions CI run #22 passed all jobs

Security

• No real emk_*, evt_*, cookies, private URLs, or production logs are included
• Private-key and internal-reference scans pass
• No generated build artifacts are committed

Related Issues

• None