fix(docs): normalize board_tokens in +create response for mermaid/whiteboard content

[eggyrooch-blip]

Problem

docs +update calls normalizeDocsUpdateResult after executing, which surfaces board_tokens in the response when the markdown contains mermaid/plantuml/whiteboard blocks. docs +create is missing the same call.

As a result, a caller who creates a document with mermaid diagrams via +create cannot know how many whiteboards were created or retrieve their tokens — even though the exact same information is available from the underlying MCP response.

Repro:

lark-cli docs +create --title "test" --markdown $'```mermaid\nflowchart LR\n  A-->B\n```'
# board_tokens is absent from output

lark-cli docs +update --doc <id> --mode append --markdown $'```mermaid\nflowchart LR\n  A-->B\n```'
# board_tokens is present in output ✓

Fix

Call normalizeDocsUpdateResult in DocsCreate.Execute after CallMCPTool, identical to how DocsUpdate.Execute does it. One-line change.

Notes

• normalizeDocsUpdateResult (and its helpers isWhiteboardCreateMarkdown, normalizeBoardTokens) live in the same doc package and are accessible without any export changes.
• No behavior change when markdown contains no mermaid/whiteboard blocks (normalizeDocsUpdateResult is a no-op in that case).

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}