Support setting issue dependencies in linear-import via CLI and CSV

[JavierPiedra]

Request: allow defining blocks and blocked_by relationships during import.

Problem
• CSV import ignores dependencies
• Requires manual linking or API scripts post-import
• Breaks atomic setup of large backlogs

Proposed Solution
• Add optional columns:
• Blocks
• Blocked By
• Accept comma-separated issue identifiers
• Resolve by:
• External ID
• Title + Team
• Or explicit Issue ID

CLI Example

linear-import --file backlog.csv --team ENG

CSV columns:

Title, Description, Blocks, Blocked By

Acceptance Criteria
• Dependencies created in same import batch
• Order-independent resolution
• Clear error output for missing references

Why it matters
• Enables deterministic backlog bootstrapping
• Improves CI-style project provisioning
• Eliminates fragile post-processing scripts

[linear-code]

LIN-59720