docs/hooks-guide.md documents 6 of 10 hook scripts

[dstolts]

Problem

docs/hooks-guide.md opens with "JitNeuro ships 6 hooks" and the "Installed Hooks" section documents 6 (PreCompact save, session-id write, heartbeat, post-compact recovery, branch protection, session-end auto-save). The template ships 10 hook scripts in templates/hooks/. The four undocumented ones:

• session-start-post-clear.sh -- SessionStart (matcher: clear) post-clear session picker
• session-start-scheduled-agents.sh -- SessionStart spawner for enabled scheduled agents
• pre-agent-register.sh -- PreToolUse, registers a sub-agent before dispatch (dashboard tracking)
• post-agent-complete.sh -- PostToolUse, marks a sub-agent complete (dashboard tracking)

Why it matters

The hooks guide is the canonical reference for what each hook does and how to configure it. Adopters reading it will not know post-clear recovery, scheduled-agent spawning, or sub-agent dashboard tracking exist or how the hook events are wired. W19 fixed the count strings repo-wide (#37); this issue is the content gap -- four hook sections need to be added to the guide (event, script, timeout, what-it-does, why-it-matters), and the intro "6 hooks" updated to "10 hook scripts / 9 hook events".

Acceptance criteria

• docs/hooks-guide.md documents all 10 hook scripts with the same section structure as the existing 6
• Intro line reflects "10 hook scripts / 9 hook events"
• ## Future Hooks (Planned) section reconciled (move any now-shipped hooks out of "planned")

Notes

Low priority -- localhost dev-tool / lifecycle plumbing, not a correctness gap. Surfaced by repo-jitneuro weekly scan 2026-W19, Scan 5 (undocumented features).