Stop no-op compaction heartbeat

Deleted the guarded compact-idle-codex-tasks heartbeat after three live task audits established that heartbeat runners do not expose a native context-compaction operation; this prevents indefinite no-op retries while preserving every task and writer lock.

Scope and changes

• Host: rdmsm4x
• Deleted through the supported Codex automation control: /Users/richh/.codex/automations/compact-idle-codex-tasks/automation.toml
• No Codex task, rollout, writer lock, repository, worktree, process, or source file was deleted or modified.
• No compaction was claimed or simulated.

Verification

• The live visible Codex task list was enumerated on each heartbeat run; active tasks were skipped.
• The callable tool registry contained no native compact or thread-compact operation on three consecutive runs.
• The supported automation deletion returned deleteStatus: deleted for automation ID compact-idle-codex-tasks.

Undo and owner action

• Recreate the heartbeat only if the runner later exposes a first-class native compaction operation.
• Until then, initiate Compact from the owning ChatGPT/Codex task interface after each target task becomes idle. Do not delete or bypass writer locks.