fix(compound-engineering): reduce /ce:review context pressure

[Neo1228]

Fixes #166.

Summary

/ce:review was fanning broad PR context out to every spawned reviewer. On larger or high-effort reviews, that makes compaction/context-limit failures much more likely before the agents get to the risky code.

This PR reduces that pressure while keeping the normal review flow intact:

• require a compact review packet before agent fan-out
• pass the packet, project review context, and exact file paths instead of full PR content
• dedupe configured agents against always-on reviewers
• add staged follow-up guidance for large PRs or visible context pressure
• avoid running code-simplicity-reviewer twice
• keep setup from writing always-on agents back into review_agents

Why this is a safe fix

• scope is prompt/workflow content plus metadata and tests; there is no runtime library change
• normal-sized PRs keep the same review surface, but with less duplicated context
• large-PR handling becomes narrower and more targeted instead of re-broadcasting the full PR to every agent
• generated compound-engineering.local.md guidance now matches actual /ce:review runtime expectations

Validation

• bun test
• Result: 316 passed, 0 failed
• Added CLI integration coverage that converts the real plugins/compound-engineering plugin into a temp Codex home and verifies the generated ce-review prompt/skill plus setup skill preserve the new guardrails
• Manual conversion smoke: bun run src/index.ts convert plugins/compound-engineering --to codex --codex-home <tmp>
• Manual conversion smoke: bun run src/index.ts convert plugins/compound-engineering --to opencode --output <tmp>
• Planning-stage Codex smoke in a temporary worktree with duplicate review_agents config confirmed the revised prompt reads local config and branch diff metadata before reviewer planning

Files changed

• plugins/compound-engineering/commands/ce/review.md: compact packet step, deduped base agent set, staged large-PR guidance, tighter conditional-agent inputs
• plugins/compound-engineering/skills/setup/SKILL.md: updated review-depth copy and removed always-on agent duplication
• tests/compound-review-command.test.ts: source-content regression checks for packet + dedupe behavior
• tests/cli.test.ts: Codex conversion integration check for the actual compound-engineering plugin output
• plugins/compound-engineering/CHANGELOG.md: release note for issue Context limit reached in review agents #166
• plugin metadata version bumps

Remaining caveat

This change improves the prompt contract and verifies that the contract survives real conversion output, but a fully deterministic end-to-end multi-agent /ce:review run is still not something the automated suite can assert. The new coverage is aimed at the highest-risk regression points for this issue: packet creation guidance, agent dedupe, large-PR staging instructions, and setup/runtime alignment.