feat: stack parallel agents vertically

[Jason-Adam]

Summary

• Each subagent now renders on its own line instead of being joined horizontally with " | ", making parallel agent activity much easier to read
• Removed the fixed 25-character agent name width cap — full names are shown, with the render pipeline's per-line ANSI truncation as the safety net
• Fixed pre-commit go-vet hook to work correctly in git worktrees by using a local system hook instead of the archived dnephin/pre-commit-golang go-vet

Test plan

• make check passes (fmt + vet + tests)
• make test-race passes
• Visual verification with live parallel subagents

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR updates the HUD renderer so parallel subagents are displayed as a vertical stack (one agent per line) rather than a single horizontally-joined segment, and adjusts tooling config for go vet in worktrees.

Changes:

• Add multi-line support to widget results via WidgetResult.ExtraLines and emit those extra lines from Render().
• Update the agents widget to return the first agent as the main segment and additional agents as ExtraLines (removing widget-level name width capping / “+N more” behavior).
• Switch pre-commit go-vet hook to a local/system hook for worktree compatibility.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
internal/render/widget/agents.go	Switch agents rendering to vertical stacking using ExtraLines and remove fixed name truncation.
internal/render/widget/widget.go	Extend WidgetResult with ExtraLines for multi-row widget output.
internal/render/render.go	Emit ExtraLines after the main rendered line, applying truncation per extra line.
internal/render/widget/widget_test.go	Update agents widget tests to validate stacking/ExtraLines behavior.
internal/render/widget/agents_test.go	Rewrite agents tests around stacked output and removal of widget-level truncation.
.pre-commit-config.yaml	Replace go-vet hook with a repo: local system hook.

Comments suppressed due to low confidence (1)

internal/render/widget/widget.go:37

• WidgetResult.IsEmpty() ignores ExtraLines. With the new multi-line capability, a widget could legitimately have empty Text/PlainText but non-empty ExtraLines and still be considered "empty" (and therefore skipped). Update IsEmpty to also consider len(ExtraLines) == 0.

// IsEmpty reports whether the result has no content to display.
func (w WidgetResult) IsEmpty() bool {
	return w.Text == "" && w.PlainText == ""
}

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