fix(export): send credentials and surface server error on USFM export

[henrique221]

Part of eten-tech-foundation/fluent-api#195.

Summary

useExportUsfm was the only API call in the app that omitted
credentials: 'include'. It worked only because the export endpoint was
unauthenticated; once fluent-api requires auth
(eten-tech-foundation/fluent-api#189), the request would 401 and the editor
export would break.

• Add credentials: 'include' so the session cookie is sent.
• Parse the JSON error body (supports both the { message } envelope and the
  USFM route's { error } shape) and surface it, so ExportProjectDialog shows
  the actual reason (e.g. "Invalid book IDs", "No books available") instead of a
  hardcoded "Export Failed". The dialog already had the inline error UI + logging.

⚠️ Release coupling

This must deploy with or before fluent-api#189's auth change, or the editor
export will 401.

Test plan

• pnpm typecheck
• pnpm lint (changed files)
• pnpm test — 38/38 pass

Summary by CodeRabbit

Bug Fixes

• Improved error messaging for project export operations. When exports encounter failures, users now receive specific, actionable error details instead of generic failure messages. This provides clearer information to help users understand what went wrong and resolve export issues more effectively.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: 4d695713-c8d5-42a1-bdbc-bb15b352a185

📥 Commits

Reviewing files that changed from the base of the PR and between 29325ef and 249bd71.

📒 Files selected for processing (2)

• src/features/projects/components/ExportProjectDialog.tsx
• src/features/projects/hooks/useExportUsfm.ts

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📝 Walkthrough

Walkthrough

The USFM export hook gains a parseExportError helper that parses failed HTTP responses as JSON to extract a message or error field, falling back to a default string. The fetch call now includes credentials: 'include'. The export dialog's catch block is updated to display the error's message property when the thrown value is an Error.

Changes

USFM Export Error Handling

Layer / File(s)	Summary
Server error parsing and credential forwarding src/features/projects/hooks/useExportUsfm.ts	Adds DEFAULT_EXPORT_ERROR constant and parseExportError(response) helper that attempts response.json() and returns message or error from the body, falling back to the default. Updates exportUsfmRequest to pass credentials: 'include' and throw new Error(await parseExportError(response)) on non-OK responses.
Export dialog error display src/features/projects/components/ExportProjectDialog.tsx	Changes the catch block error state assignment to use err.message when the caught value is an Error instance, with a fallback to 'Export Failed'.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Possibly related issues

• Export: surface failures to users + log to Azure (sync USFM export) fluent-api#195: The changes directly implement what this issue describes — adding credentials: 'include' to the USFM export fetch call and surfacing actionable server error messages in the export dialog instead of a generic fallback string.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main changes: adding credentials to the fetch call and improving error handling to surface server errors in USFM export.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/195-usfm-export-credentials-error-ux

Warning

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