@lead: externalize agent.yml inline scripts into .gitea/workflows/scripts/*.sh

Rebased onto the per-agent skill-scoping change so PR #25 carries both:
- route.sh keeps the registry 'skills' allow-list and emits skills as a step output
- install-opencode.sh writes the permission.skill block (deny-all + allow listed)

Pure refactor otherwise: each step's shell moves to its own file, called via
bash "$SCRIPTS/<name>.sh". The two extracted SKILL.md bodies are byte-identical to
main; routing/config/publish behavior is unchanged. Because this is a reusable
workflow (workflow_call) the runtime checkout is the caller's repo, so agent.yml now
checks THIS repo out into .agents-workflow/ (pinned @main) and points $SCRIPTS there.

README.md

@@ -47,6 +47,18 @@ jobs:
 That's the whole per-repo footprint. All the logic (agent registry, routing, delegation,
 reactions, PR/issue plumbing) lives here in `agent.yml`.
 
+## Repo layout
+
+`agent.yml` is kept thin: each step's shell lives in its own file under
+`.gitea/workflows/scripts/` (`route.sh`, `install-opencode.sh`, `skill-node1-ssh.sh`,
+`skill-gitea-api.sh`, `fetch-images.sh`, `fetch-thread.sh`, `run-agent.sh`,
+`build-activity-log.sh`, `publish.sh`), invoked as `bash "$SCRIPTS/<name>.sh"`.
+
+Because this is a **reusable** workflow (`workflow_call`), a caller run checks out the *caller's*
+repo, not this one — so those script files aren't on disk by default. `agent.yml` therefore checks
+this repo out into `.agents-workflow/` (pinned to `@main`, matching the caller's `uses: …@main`) and
+points `$SCRIPTS` at it. Keep the workflow and its scripts moving together on `main`.
+
 ## Required secrets (per repo, or org-level for all)
 
 | Secret | For |