ENG-1977 Add schema import data layer for Obsidian

[trangdoan982]

Summary

Adds the import data layer — file parsing, match planning, and apply logic. The UI modal is in the next PR.

• specImport.ts — three responsibilities co-located:
  • parseDgSchemaFile — lightweight version guard + cast (no Zod; export is the authoritative source)
  • buildSchemaImportMatchPlan — computes id and name/label mappings between the schema file and the local vault in one pass; id match first, name/label fallback second
  • applySchemaImportSelection — creates new items as provisional, skips existing matches; preserves template reference when template already exists locally

Stack

PR 4 of 5 for FEE-840. Stacks on #1263.

1. Shared foundation — ENG-1975 (ENG-1975 Define schema file contract and shared foundation for Obsidian export/import #1180)
2. Schema selection panel UI — ENG-2083 (ENG-2083 Add schema selection panel UI for Obsidian export/import #1262)
3. Schema export command — ENG-1976 (ENG-1976 Add schema export command to Obsidian #1263)
4. This PR — schema import data layer (ENG-1977)
5. Schema import UI (ENG-2084)

Test plan

• pnpm --filter @discourse-graphs/obsidian check-types passes
• parseDgSchemaFile rejects files with wrong version with a clear error
• buildSchemaImportMatchPlan id-matches first, name/label fallback second
• applySchemaImportSelection creates new items as provisional, skips duplicates
• Re-running apply on the same file creates no duplicates
• New node type retains its template reference when template already exists locally

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[linear-code]

ENG-1977

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
discourse-graph	Skipped		Jul 30, 2026 3:18am

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