feat: add configurable working directory and Claude data path

[heman22union]

Summary

Three new options, all backwards-compatible (defaults preserve existing behaviour):

• working_directory — directory Claude starts in (default /config). Useful if your work lives in a subdirectory like /config/ai_repo.
• prompt_working_directory — when true, prompts you to confirm or change the working directory on every session open, showing the last-used path as the default.
• claude_data_path — relocate ~/.claude session/config data out of /data (container-only, not visible to ha filesystem or over SMB) into a user-specified path such as /config/.claude. Makes sessions accessible over SMB and portable across HA migrations or reinstalls.

Adds scripts/pick-working-dir.sh which handles the interactive directory prompt and persists the last choice to $ANTHROPIC_HOME/last-working-dir.

Motivation

Currently the addon stores all Claude data under /data, which is the container's private persistent volume. This means session history and project files are invisible over SMB and lost if you migrate or reinstall HA. Moving data to /config solves both problems.

Test notes

Tested on 2.2.x with claude_data_path: /config/.claude and working_directory: /config/ai_repo. A few things discovered during testing worth noting for reviewers:

• All environment variables (HOME, XDG_*, ANTHROPIC_*) are derived from claude_data_path so they stay consistent — no hardcoded /data paths remain
• The last-working-dir state file is stored under $ANTHROPIC_HOME so it persists across restarts when claude_data_path points to /config

Test plan

• Addon starts normally with no options set (defaults to /config, uses /data for Claude data)
• Setting working_directory: /config/ai_repo lands Claude in that directory on open
• Enabling prompt_working_directory: true shows prompt; Enter confirms last-used dir; choice persists across restarts
• Setting claude_data_path: /config/.claude creates directory structure there and Claude stores sessions/config under it
• Sessions and auth survive addon restart when claude_data_path is under /config
• Existing auth files still migrate correctly when claude_data_path is set