Multi-repo hook output is unbounded

[JordanCoin]

Problem

hookSessionStartMultiRepo in cmd/hooks.go:711 runs codemap --depth 2 per child repo and pipes directly to stdout. This bypasses the new adaptive depth + 60KB hard cap introduced for single-repo hooks.

A mono-repo parent with many child repos (e.g. 50+) could still produce large output that eats into Claude's context window.

Suggested fix

Apply the same output capture + truncation pattern used in hookSessionStart — write to a strings.Builder, enforce limits.MaxContextOutputBytes, truncate at a clean line boundary.

Context

Flagged during review of #22 (fix/context-size-limits). Not blocking since --depth 2 keeps individual repo output small, but it's the one path that bypasses the new limits.

[JordanCoin]

May have been solved with this #27