feat(experiment): create new scicat experiments with default keywords

[Junjiequan]

Description

Set keywords on new SciCat experiments

New experiments created in SciCat by the connector now get keywords, configurable with SCICAT_NEW_EXPERIMENT_KEYWORDS (comma separated). When the variable is unset or empty, they get WF_01_00, which puts every new experiment into the ESS experiment data publication workflow.

• Keywords are sent on create only. SciCat replaces the whole keyword list on update, so sending them on every User Office update would wipe the labels the workflow sets later (WF_01_01, …).
• validateEnv.ts and sample.env document the new variable.

Tests

• The configured keyword is set, and a comma-separated list is split and trimmed.
• Falls back to WF_01_00 when the variable is unset or empty.
• Update DTOs never include keywords.
• The create-DTO snapshots now include keywords.

🤖 Generated with Claude Code

Motivation and Context

How Has This Been Tested

Fixes

Changes

Depends on

Tests included/Docs Updated?

• I have added tests to cover my changes.
• All relevant doc has been updated