Refine startup error handling to avoid false storage disconnect warnings

[JackWilb]

Does this PR close any open issues?

Closes #1153

Give a longer description of what this PR addresses and why it's needed

This changes the participant startup flow so we only show Storage Disconnected for real storage-engine failures.

In Shell.tsx, startup metadata collection now safely handles missing browser APIs like screen.orientation instead of throwing. Startup failures are classified from the actual storage engine state, and non-storage failures now seed a normal alert modal rather than incorrectly setting the storage-disconnected flag. In study dev mode, that alert shows the underlying error message; otherwise it stays generic or uses resume-specific copy when a participantId is present.

I also added a small optional initial-alert path to the store and added focused unit tests for the startup helper logic.

Provide pictures/videos of the behavior before and after these changes (optional)

Are there any additional TODOs before this PR is ready to go?

TODOs:

• Update relevant documentation
• ...

[github-actions]

A preview of 0e0510e is uploaded and can be seen here:

✨ https://revisit.dev/study/PR1164 ✨

Changes may take a few minutes to propagate.

[Copilot]

Pull request overview

Refines the participant startup flow to avoid showing “Storage Disconnected” for non–storage-engine startup errors (e.g., missing browser APIs or resume/participant lookup failures), while still surfacing actionable alerts when appropriate.

Changes:

• Adds Shell.utils helpers to safely read screen.orientation, classify storage-engine startup failures, and build initial alert-modal state.
• Extends studyStoreCreator to accept an optional initial alertModal state and introduces a shared AlertModalState type.
• Updates Shell.tsx to (a) avoid screen.orientation runtime errors and (b) seed a normal alert modal for non-storage failures; adds focused unit tests.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/store/types.ts	Introduces AlertModalState type alias and uses it in StoreState.
src/store/store.tsx	Adds optional initialAlertModal parameter to seed initial store state; tightens setAlertModal payload typing.
src/components/Shell.utils.ts	New startup helper utilities (orientation, failure classification, error messaging, initial alert state).
src/components/Shell.utils.spec.ts	New Vitest coverage for the startup helper utilities.
src/components/Shell.tsx	Uses safe orientation accessor and improved startup error classification to prevent false “storage disconnected” warnings.

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