feat(parser): capture background_tasks and session_crons from v2.1.145+ Stop/SubagentStop hooks

[delexw]

Summary

Adds background_tasks and session_crons as optional fields on the Entry struct to handle the new Stop/SubagentStop hook payload fields introduced in Claude Code v2.1.145.

Problem

Claude Code v2.1.145 (May 19, 2026) added two new fields to Stop and SubagentStop hook input payloads:

• background_tasks — array of currently-running background task descriptors
• session_crons — array of cron jobs registered for the session

Without explicit struct fields, serde silently skips these arrays on deserialization. While this does not cause parser crashes (no deny_unknown_fields is in use), the data is lost and future code cannot access it. Declaring the fields explicitly captures the payloads and makes the compat intent clear.

Changes

• src-tauri/src/parser/entry.rs: Added background_tasks: Option<Value> and session_crons: Option<Value> to Entry, both with #[serde(default)] so pre-v2.1.145 entries (where the fields are absent) default to None without error. Added 3 tests covering: Stop hook with both fields populated, pre-v2.1.145 Stop hook with neither field present, and SubagentStop hook with an empty background_tasks array and a multi-item session_crons array.
• specs/01-parser-pipeline.md: Added the two new fields to the Key Fields table.

Testing

All 400 Rust tests pass (cargo test). All 349 frontend tests pass (vitest run). cargo clippy -- -D warnings reports no issues.

Fixes #106