fix: prevent Git Bash path corruption for Docker volumes

[bfmhno3]

Refactor container data paths to use double-slash prefix (//var/...) to:

• Avoid Git Bash's automatic POSIX-Windows path conversion
• Fix critical mount error on Windows environments: "Error: mount source path too many colons"
• Maintain Linux container compatibility
• Resolves Overleaf toolkit init failure when using Git Bash

Description

A detailed description is provided in #379

Related issues / Pull Requests

#379

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