@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.

.gitea/workflows/scripts/build-activity-log.sh

@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+# Build activity log (tool calls + reasoning) from the event stream into /tmp/activity_log.md.
+# Only dev agents (mode=pr) get an activity-log comment — comment-only roles (pm/qa)
+# do no tool calls, so a trail would be empty/noise.
+#
+# Required env (provided by the workflow step): MODE
+set -u
+
+if [ "$MODE" != "pr" ]; then
+  echo "skipping activity log for comment-mode agent"; : > /tmp/activity_log.md; exit 0
+fi
+jq -r '
+  def trunc(n): if length > n then (.[0:n] + "…") else . end;
+  select(.type=="tool_use" or .type=="text") |
+    if .type=="text" then
+      "💬 " + ((.part.text // "") | trunc(4000))
+    else
+      (.part.tool // "?") as $t |
+      ((.part.state.title // (.part.state.input | tojson | trunc(160)) // "")) as $title |
+      "🔧 **" + $t + "**: `" + ($title | trunc(240)) + "`"
+    end
+' /tmp/events.jsonl > /tmp/activity_log.md 2>/dev/null || true
+n=$(wc -l < /tmp/activity_log.md 2>/dev/null || echo 0)
+echo "activity log: $n entries"
+[ "$n" -eq 0 ] && : > /tmp/activity_log.md
+head -3 /tmp/activity_log.md