feat: add IoTDB datasource support

[HTHou]

Summary

• add IoTDB as a built-in timeseries datasource and register its cache/router wiring
• implement IoTDB table-model metadata/query support and filter system databases from schema discovery
• fix embedded explorer behavior for IoTDB, including datasource routing and chart time normalization

Testing

• go build ./dskit/iotdb ./datasource/iotdb ./center/router ./dscache
• npm run build (in the separate frontend workspace used to regenerate embedded assets)

Notes

• the frontend source lives in a sibling workspace, so the repository-side change updates the embedded frontend assets consumed by this repo
• the corresponding frontend PR is Add standalone IoTDB frontend support n9e/fe#2078

[710leo]

👍 After the frontend PR modifications are completed, we'll handle the PR together.

[710leo]

@HTHou front/statik/statik.go The statik tool generates binary embedded files based on frontend build artifacts. These should typically be updated separately by the frontend build process and should not be mixed into functional PRs.

[HTHou]

Hi @710leo, happy to see this PR is merged. I also updated implementation recently in the branch https://github.com/HTHou/nightingale/tree/codex/iotdb-auto-downsample and https://github.com/HTHou/nightingale-fe/tree/codex/iotdb-auto-downsample. May I need to submit them again?

[710leo]

@HTHou For the nightingale project, you can submit a new pull request (PR) to the iotdb branch. For the n9e/fe project, you can continue to update the original PR.