feat: [IEL-186] Expired document in blob storage case

[freddi301]

Short description

When entering the digital signature flow the list of pdf documents are reuqested and obtained as urls with expiration to download them.
This PR aims to replicate that aspect.

List of changes proposed in this pull request

• add an expiration url query parameter to mimic document urls with expiration like in production
• check for expiration when getting document pdf file, simulate blob storage response

How to test

• start developer server
• start app pointing to developer server
• in the app complete an "firma con io" signature requets under 5 minutes, it should go fine
• second case, wait 5 minutes after opening a signature request, expected effects
  • pdf documents will not load corectly if navigating in the flow
  • you can't submit a signature correctly in the final step (error screen show on the last CTA)

[Copilot]

Pull request overview

This PR updates the FCI dev-server endpoints to better simulate production-like expiring document URLs and blob-storage-style expiration failures during the digital signature flow.

Changes:

• Adds an expiration query parameter to FCI document URLs returned by the signature request detail endpoint.
• Introduces an expiration check on the static PDF serving endpoint, returning a 403 XML error similar to Azure Blob Storage when expired.
• Extends the messages FCI config schema/defaults with documentExpirationDurationSeconds.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
src/routers/features/fci/index.ts	Appends an expiration timestamp to document URLs and simulates blob-style 403 responses for expired downloads.
src/features/messages/types/messagesConfig.ts	Adds documentExpirationDurationSeconds to the io-ts config type for FCI responses.
src/config.ts	Provides a default value for documentExpirationDurationSeconds in the dev-server default config.

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[Ladirico]

LGTM!