Enable non-root Docker runtime for repository creation paths

[Copilot]

Running Borgitory in Docker as a non-root UID/GID could fail during repo creation because Borg runtime state paths were not guaranteed writable outside root. This change makes container startup resilient to non-root permissions while keeping root behavior unchanged.

• Entrypoint runtime defaults (non-root-safe)

  • start.sh now requires a writable HOME and fails startup with a descriptive error if HOME is unset or not writable.
  • If BORG_BASE_DIR is unset, startup defaults it to /cache/borg.
  • Startup now fails fast with descriptive errors when BORG_BASE_DIR is not writable.
  • Emoji output was removed from startup/debug/error messages.

• Image filesystem preparation

  • Docker runtime image now creates /cache alongside /app/data, enabling a predictable mount target for Borg state under non-root users.

• Compose/docs updates for UID/GID mapping

  • README Docker Compose example now documents optional user: "${UID}:${GID}", adds /cache volume usage, and clarifies setting UID/GID before launch.

# start.sh (effective behavior)
if [ -z "${HOME}" ]; then
  echo "ERROR: HOME is not set..."
  exit 1
fi

if [ -z "${BORG_BASE_DIR}" ]; then
  export BORG_BASE_DIR="/cache/borg"
fi

# fail if not writable

[mlapaglia]

@copilot don't fallback to /tmp, just fail to start with a descriptive error message. get rid of the stupid emojis.

[Copilot]

@copilot don't fallback to /tmp, just fail to start with a descriptive error message. get rid of the stupid emojis.

Updated in commit cfae5ba. start.sh no longer falls back to /tmp; it now fails fast with descriptive errors when HOME or BORG_BASE_DIR are not writable, and I removed emojis from startup/debug/error messages.

[Copilot]

Pull request overview

This PR improves Borgitory’s Docker startup behavior when running as a non-root UID/GID by ensuring Borg runtime state directories are writable (or failing fast with clear errors), and updating container/docs to support a /cache mount point.

Changes:

• Add startup checks in start.sh to require writable HOME and BORG_BASE_DIR, defaulting BORG_BASE_DIR to /cache/borg when unset.
• Create /cache in the runtime image filesystem.
• Update README Compose example to document optional UID/GID user mapping and a /cache volume.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
start.sh	Adds writable-dir checks for HOME and BORG_BASE_DIR, removes emoji from logs.
Dockerfile	Creates /cache directory in the runtime image.
README.md	Updates Docker Compose example and notes for non-root runs and /cache volume.

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.68%. Comparing base (0ee810d) to head (3ffa476).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #237   +/-   ##
========================================
  Coverage    79.68%   79.68%           
========================================
  Files          147      147           
  Lines        13870    13870           
========================================
  Hits         11052    11052           
  Misses        2818     2818           

Flag	Coverage Δ
e2e	0.00% <ø> (ø)
integration	45.85% <ø> (ø)
unit	71.17% <ø> (ø)

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