agents: discussion mode — devs talk in threads; building starts only on explicit signal

Mentioning a dev agent no longer spawns a branch + PR machinery. It is a
CONVERSATION by default: the dev reads what it needs and replies in-thread.

- route.sh: workmode=build|discuss for mode=pr agents. Build ONLY on the
  explicit signals: PR-thread comments (resume), the pm delegation template
  ("please proceed with issue …" — a human can write it too), or the qa bounce
  ("please address my review …"). Everything else = discuss: no branch prep,
  no "🔨 Building" notice.
- run-agent.sh: discussion ACTION for devs (read-only consult, no edits/
  commits/markers). @pm gains 'ASK: @<dev> <question>' to consult devs before
  planning — gather feasibility/effort input, then DELEGATE when enough is
  known. One ASK per reply; never ASK+DELEGATE together.
- publish.sh: pm ASK handler posts the question as a discussion trigger; dev
  discuss path posts the reply (+run report) and skips ALL git/PR machinery
  (stray edits discarded). ASK marker stripped from visible replies.
- agent.yml: WORKMODE threaded to Run-agent + Publish. README documents it.

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

.gitea/workflows/agent.yml

@@ -198,6 +198,7 @@ jobs:
           MODEL: ${{ steps.prep.outputs.model }}
           VISION: ${{ steps.prep.outputs.vision }}
           MODE: ${{ steps.prep.outputs.mode }}
+          WORKMODE: ${{ steps.prep.outputs.workmode }}   # build | discuss (devs consulted in-thread)
           HAS_IMAGES: ${{ steps.imgs.outputs.has_images }}
           BRANCH: ${{ steps.prep.outputs.branch }}
           AUTOPILOT: ${{ steps.prep.outputs.autopilot }}   # 'true' when the issue carries the `autopilot` label
@@ -231,6 +232,7 @@ jobs:
           TOKEN_INTERN: ${{ secrets.TOKEN_INTERN }}
           NAME: ${{ steps.prep.outputs.name }}
           MODE: ${{ steps.prep.outputs.mode }}
+          WORKMODE: ${{ steps.prep.outputs.workmode }}
           NUM: ${{ github.event.issue.number }}
           TITLE: ${{ github.event.issue.title }}
           BRANCH: ${{ steps.prep.outputs.branch }}