fix(agent): apply local-skill context on the codex adapter

[tatoalo]

Problem

Local skills didn't actually apply on the Codex adapter. The agent-server sets _meta.localSkillContext (the resolved skill instructions) and leaves the raw /skill slash command in the prompt; the Claude adapter consumes that meta, dropping the /skill chunk and injecting the instructions — but the Codex adapter had no such seam, so the bare /skill reached codex-acp and the skill instructions were ignored.

Changes

• added prependLocalSkillContext to the Codex adapter, mirroring the Claude adapter's promptToClaude handling: drop the leading /skill chunk (the context already carries the user's args), prepend the resolved skill instructions as a text block, and strip the local-skill _meta before forwarding to codex-acp
• extracted the shared isLocalSkillCommandChunk helper into adapters/local-skill.ts, now imported by both the Codex and Claude adapters (previously duplicated)

[tatoalo]

• fix(agent): apply local-skill context on the codex adapter #3058 👈 (View in Graphite)
• feat(skills): auto-bundle declared skill dependencies in cloud runs #3057
• fix(cloud-task): bundle a local skill tagged on the first message #3056
• main

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[github-actions]

React Doctor found no issues in the changed files. 🎉

_{Reviewed by React Doctor for commit b901a88.}

[greptile-apps]

_{Reviews (1): Last reviewed commit: "fix(agent): apply local-skill context on..." | Re-trigger Greptile}

[github-actions]

Clean bug fix that mirrors existing Claude adapter behavior in the Codex adapter. Defensive guards prevent the broken-mix edge case, all bot review comments were addressed (guard for missing localSkillName, parameterized tests), and no API contracts, data models, or dependencies are touched.

[greptile-apps]

_{Reviews (2): Last reviewed commit: "fix(agent): apply local-skill context on..." | Re-trigger Greptile}

New commits pushed (delta classified non_linear_history) — stamphog approval dismissed; re-review running automatically.

[github-actions]

Clean bug fix that mirrors existing Claude adapter behavior in the Codex adapter. The extracted helper, defensive guard for missing localSkillName, and parameterized tests all look correct with no showstoppers.

[stamphog]

Retaining stamphog approval — delta since last review classified as merge_only.