agents: fix review findings — thread attribution, races, rescue stall, docs, CI

Fixes from a full repo review:

- fetch-thread.sh: attribute每 comment to its REAL author (@pm/@qa/… — agents
  post as their own users now); the old "🤖 @name line at the top" hint pointed
  at headers we removed, leaving every teammate comment anonymous. Also strip
  the hidden loop-prevention marker from bodies (prompt noise).
- agent.yml: per-issue concurrency group (queued, no cancel) — two quick
  comments on one issue no longer race the same ai/issue-N branch.
- rescue-pr.sh: after opening a rescue PR, hand it back into the flow with an
  unmarked @pm trigger (the pm→qa choreography previously stalled silently on
  any rescued run); drop the old "🤖 **@name**" header style; add ops to the
  token case; mark the status note with the hidden marker.
- README: token table said "@qa merges / TOKEN_QA needs write:repository" —
  inverted since the PM-orchestrated flow (@pm merges, autopilot only; @qa is
  read-only). Updated the agent table (descs, node1-ssh moved to homelab) and
  added a "How a task flows" section.
- agents.json: pm/qa descs now describe the orchestrator/reviewer roles (these
  feed the roster prompt agents route by).
- NEW ci.yml: bash -n + shellcheck(-S error) on every script, YAML-parse on
  every workflow, agents.json schema check — the ${x:-{}} brace bug would have
  been caught here before it shipped.
- install-opencode.sh: pin opencode (default 1.17.13, override via
  OPENCODE_VERSION) — a breaking release no longer takes down every agent.
- build-activity-log.sh: ollama/ollama-cloud models are subscription-billed
  (no $/token exists) — label the footer "subscription" instead of a
  misleading $0.0000; metered (anthropic) models keep the real dollar cost.
- route.sh: document that mention-priority is list-order and load-bearing for
  the flow's trigger comments.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.gitea/workflows/scripts/install-opencode.sh

@@ -5,7 +5,11 @@
 #   GITHUB_PATH HOME
 set -eu
 
-curl -fsSL https://opencode.ai/install | bash
+# PIN the opencode version: an unpinned `latest` means a breaking release (CLI flags, or the
+# --format json event schema that build-activity-log.sh parses) breaks every agent in every repo
+# at once. Bump deliberately by changing this default (or set OPENCODE_VERSION in the step env).
+OPENCODE_VERSION="${OPENCODE_VERSION:-1.17.13}"
+curl -fsSL https://opencode.ai/install | bash -s -- --version "$OPENCODE_VERSION"
 echo "$HOME/.opencode/bin" >> "$GITHUB_PATH"
 mkdir -p ~/.config/opencode
 # Playwright browser MCP only for agents that need to drive a web app