fix(ohmyzsh): unshallow clone after install so omz update works

[gitricko]

Problem

When users run omz update (the prompt that fires when a new omz release is detected), it fails with:

[oh-my-zsh] Would you like to update? [Y/n] Y
Updating Oh My Zsh
error: Could not read <hash>
error: could not parse commit <hash>
There was an error updating. Try again later?

Root cause

The omz installer script (ohmyzsh/tools/install.sh line 317) does:

git fetch --depth=1 origin

So ~/.oh-my-zsh ships as a shallow clone. omz update later runs git pull, which needs to fetch the parent commits of the local tip to do the merge. Those parents are outside the depth-1 boundary, and once GitHub GCs them on origin (or force-pushes rewrite history), they're permanently unreachable — hence the "Could not read" error pointing at commit hashes that are merge tips' parents.

Fix

After the unattended install, run git fetch --unshallow origin to convert the depth-1 clone into a full clone. Guarded with:

• if [ -d "$HOME/.oh-my-zsh/.git" ] — only runs if omz actually installed
• 2>/dev/null || true — never blocks the boot path on network/partial-state issues

Diff

     runuser -l abc -c 'sh -c "$(curl -fsSL https://raw.githubusercontent.com/ohmyzsh/ohmyzsh/master/tools/install.sh)" --unattended'

+    # The omz install.sh does `git clone --depth=1`, which makes `omz update`
+    # fail later with "Could not read <hash>" when parents get GC'd on origin.
+    # Unshallow to a full clone so future updates work reliably.
+    if [ -d "$HOME/.oh-my-zsh/.git" ]; then
+        runuser -l abc -c 'cd "$HOME/.oh-my-zsh" && git fetch --unshallow origin 2>/dev/null || true'
+    fi
+
     ZSHRC="$HOME/.zshrc"

Cost

• Image size: +~5-10 MB (full omz history is ~80 MB vs ~3 MB depth-1)
• Build time: +~10-20s (full git fetch vs depth-1)
• Runtime: omz update works reliably for the lifetime of the container

Test plan

• Rebuild image, confirm omz version shows is_repo: true, is_clean: ...
• git -C ~/.oh-my-zsh rev-parse --is-shallow-repository → false
• Trigger omz update — should complete without "Could not read" errors

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