fix(watch): bound sidecar delivery watches away from Resource payloads

[schickling-assistant]

The DING sidecar and the codex/opencode delivery pumps recursively
watched each agent dir. A recursive registration eagerly allocates one
inotify watch per directory BEFORE any callback filtering, and agent dirs
contain resources/ payload trees — the same unbounded-traversal class
the supervisor hit in #314, one level down.

• watch_delivery_inputs now makes two shallow subscriptions: a
  non-recursive watch on the agent dir (status file) plus a recursive
  watch on resources/inbox, which is st2-owned and bounded by delivery
  traffic rather than payloads.
• run_ding anchors its watch on the inbox itself and creates it up front,
  instead of falling back to a recursive walk over the whole agent dir
  when the inbox did not exist yet.
• All remaining recursive registrations construct their watcher with
  follow_symlinks(false): a symlink must never carry traversal outside
  the watched boundary.

Closes #314 (sidecar instance).

Co-authored-by: schickling-assistant schickling-assistant@users.noreply.github.com
agent-identity: unknown
agent-persona: generalist
agent-supervisor: unavailable
agent-tool: OMP
agent-tool-version: 18.0.3
agent-runtime: OMP 18.0.3
tooling-profile: dotfiles@f33cd9c-dirty

---

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[schickling-assistant]

@codex Please review this PR.

Posted on behalf of @schickling

field	value
agent_identity	unknown
agent_persona	generalist
agent_supervisor	unavailable
agent_tool	OMP
agent_tool_version	18.0.3
agent_runtime	OMP 18.0.3
tooling_profile	dotfiles@f33cd9c-dirty

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Delightful!

Reviewed commit: 11bcf5de98

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