agent: move TokenUsage/SkillEvent to leaf types package (detangle)

[Soph]

https://entire.io/gh/entireio/cli/trails/624

Stacked on #1481. Review/merge the lower PRs first; this diff is against that branch.

What

Dependency detangle that unblocks relocating the checkpoint contract to api/checkpoint (#1433). TokenUsage and the SkillEvent cluster move from the heavy agent package into the existing leaf agent/types package; transparent aliases stay behind in agent.

// in agent, after the move:
type TokenUsage = types.TokenUsage
type SkillEvent = types.SkillEvent   // + SkillEventSkill/Source/TranscriptAnchor/Collapse

Why

The checkpoint metadata DTOs (CommittedMetadata, CheckpointSummary, …) embed TokenUsage/SkillEvent. While those types lived in agent, any consumer of the checkpoint contract transitively imported agent and its TUI/launch/review fan-out — so the contract could never become a clean standalone package. After this move, checkpoint.go references types.* and drops its agent import.

Blast radius: zero behavioral change

• The ~34 files using agent.TokenUsage / agent.SkillEvent keep compiling unchanged — the aliases are identical types, JSON tags are preserved verbatim, no method sets involved.
• Constants (SkillEventType*, SkillSignal*, …) and the SkillEventExtractor interface stay in agent.
• CalculateTokenUsage stays in agent, still returns *TokenUsage (the alias).

Next in the stack

PR3b (stacked on this): relocate the now-agent-free contract (interfaces + DTOs) to github.com/entireio/cli/api/checkpoint and rewrite import paths.

Verification

go build ./..., all tests compile, mise run fmt (clean), mise run lint (0 issues), and suites for agent/..., checkpoint/..., cmd/entire/cli, strategy, session all green.

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Note

Low Risk
Pure type relocation with identical JSON tags and aliases; no runtime or serialization behavior change.

Overview
Moves TokenUsage and the SkillEvent struct family out of agent into the leaf agent/types package so checkpoint metadata can depend on those DTOs without pulling in the full agent package.

checkpoint now types TokenUsage / SkillEvent fields as types.* and drops its agent import. agent keeps transparent type aliases (type TokenUsage = types.TokenUsage, same for SkillEvent and related types) so existing agent.TokenUsage / agent.SkillEvent call sites keep compiling unchanged. Skill constants and SkillEventExtractor stay in agent.

^{Reviewed by Cursor Bugbot for commit 61d2fb5. Configure here.}

[Copilot]

Pull request overview

This PR detangles the checkpoint contract from the heavier agent package by relocating the TokenUsage and SkillEvent DTOs into the leaf cmd/entire/cli/agent/types package, while preserving backward compatibility via type aliases in agent.

Changes:

• Updated checkpoint metadata DTOs to use types.TokenUsage / types.SkillEvent and removed the agent import from the checkpoint contract.
• Added TokenUsage and the SkillEvent struct family to cmd/entire/cli/agent/types.
• Kept existing call sites compiling by adding transparent aliases in cmd/entire/cli/agent.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
cmd/entire/cli/checkpoint/checkpoint.go	Switches checkpoint DTO fields from agent.* to leaf types.*, dropping the heavy agent import.
cmd/entire/cli/agent/types/token_usage.go	Introduces the leaf types.TokenUsage DTO (JSON schema preserved).
cmd/entire/cli/agent/types/skill_events.go	Introduces the leaf types.SkillEvent DTO family (JSON schema preserved).
cmd/entire/cli/agent/types.go	Replaces in-package TokenUsage definition with an alias to types.TokenUsage.
cmd/entire/cli/agent/skill_events.go	Replaces in-package SkillEvent definitions with aliases to types.* while retaining constants/interfaces in agent.

The base branch was changed.