Add Claude integration hooks and history-end locking

[ellie]

This adds Claude Code integration support behind a new [integrations] settings block (claude = true by default) and documents it in the sample config and docs.

It wires auto-configuration of Claude hooks plus hook payload capture in Atuin, gated by integrations.claude and presence of claude in PATH.

Trigger points are daemon startup and direct-db history end (not init, and not daemon-backed history end).

It also adds a global history-end.lock for all history-end commands, alongside a separate lock for Claude settings updates, to prevent race conditions.

Checks

• I am happy for maintainers to push small adjustments to this PR, to speed up the review cycle
• I have checked that there are no existing pull requests for the same thing

[greptile-apps]

Greptile Summary

Adds Claude Code integration with auto-hook configuration. Sets up Bash tool capture via PostToolUse hooks, adds history-end locking to prevent race conditions, and gates everything behind integrations.claude (defaults true).

• Test compilation error on line 1326 (struct spread not valid)
• Implementation handles both new __capture-claude-hook command and legacy atuin-capture.sh detection
• Lock files prevent concurrent history-end operations and Claude settings updates
• Hook auto-configuration only triggers when claude binary is in PATH

Important Files Changed

Filename	Overview
crates/atuin/src/command/client/history.rs	Added Claude hook capture, history-end locking, and comprehensive tests. One test has a compilation error with struct spread syntax.
crates/atuin-client/src/settings.rs	Added Integrations struct with claude field defaulting to true.
crates/atuin/src/command/client/daemon.rs	Added Claude hook auto-configuration on daemon startup.

_{Last reviewed commit: 3cc03ed}

[greptile-apps]

_{6 files reviewed, 1 comment}

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