Make sure TC sync completes before select book in reload (BL-16327)

[JohnThomson]

This change is 

[cubic-dev-ai]

No issues found across 3 files

_{Re-trigger cubic}

[cubic-dev-ai]

No issues found across 3 files

_{Re-trigger cubic}

[andrew-polk]

@andrew-polk reviewed 3 files and all commit messages, and made 1 comment.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on JohnThomson).

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src/BloomExe/Workspace/WorkspaceView.cs line 221 at r1 (raw file):

        // If we're loading a team collection, we need to do that...with its progress dialog...
        // before anything else, and we'll need to close the splash screen to make room for
        // that dialog.
        // Note, this not put into _startupActions...it should never be disabled.

I'm not sure how much of this comment is even meaningful anymore, but it is at least misplaced now.

[JohnThomson]

@JohnThomson made 1 comment.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on andrew-polk).

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src/BloomExe/Workspace/WorkspaceView.cs line 221 at r1 (raw file):

Previously, andrew-polk wrote…

        // If we're loading a team collection, we need to do that...with its progress dialog...
        // before anything else, and we'll need to close the splash screen to make room for
        // that dialog.
        // Note, this not put into _startupActions...it should never be disabled.

I'm not sure how much of this comment is even meaningful anymore, but it is at least misplaced now.

Done.

[greptile-apps]

Greptile Summary

This PR ensures that, for Team Collection workspaces, book selection at startup does not proceed until TC sync has finished — fixing a bug where a remotely renamed book could be selected before its local files were fully updated. It introduces a derived milestone "startupBookSelectionReady" that is only set once both "teamSyncCompleted" and "collectionButtonsDrawn" have been reached, and adds a _milestoneLock to guard the milestone HashSet from concurrent mutation.

• StartupScreenManager gains ClearStartupMilestone, StartupMilestoneHasBeenReached, a private EnsureDependentMilestonesAreSet, and a _milestoneLock protecting all _milestones accesses.
• TeamCollection.SynchronizeRepoAndLocal signals "teamSyncCompleted" after its try/catch so the milestone is always set regardless of sync outcome.
• WorkspaceView.OnLoad clears the three relevant milestones at the start of each load, immediately sets "teamSyncCompleted" for non-TC collections, and waits on "startupBookSelectionReady" instead of the old "collectionButtonsDrawn".

Important Files Changed

Filename	Overview
src/BloomExe/MiscUI/StartupScreenManager.cs	Adds thread-safe milestone locking, a new derived "startupBookSelectionReady" milestone, ClearStartupMilestone, and a public StartupMilestoneHasBeenReached check. Logic is correct; minor undocumented invariant in EnsureDependentMilestonesAreSet.
src/BloomExe/TeamCollection/TeamCollection.cs	Adds StartupMilestoneReached("teamSyncCompleted") after the try/catch block so it fires regardless of sync success or failure — correct placement.
src/BloomExe/Workspace/WorkspaceView.cs	Switches SelectBookAtStartup wait milestone to "startupBookSelectionReady", clears milestones at start of OnLoad, and immediately sets "teamSyncCompleted" for non-TC collections. The third ClearStartupMilestone("startupBookSelectionReady") call is redundant but harmless.

_{Reviews (1): Last reviewed commit: "Make sure TC sync completes before selec..." | Re-trigger Greptile}

[greptile-apps]

EnsureDependentMilestonesAreSet only fires on addition, never on re-check

startupBookSelectionReady is derived from two prerequisites, but EnsureDependentMilestonesAreSet is only invoked inside StartupMilestoneReached. If both prerequisites are already set when a caller invokes ClearStartupMilestone("startupBookSelectionReady") directly (without clearing either prerequisite), startupBookSelectionReady is removed and no code path re-derives it until the next StartupMilestoneReached call. The current OnLoad flow is safe, but a brief comment on this invariant would help future maintainers.

[andrew-polk]

@andrew-polk reviewed 1 file and all commit messages, and resolved 1 discussion.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on JohnThomson).