refactor: setup-plugins writes config via openclaw config set

Instead of just exporting env vars (which are ephemeral), the script
now calls 'openclaw config set' to persist each plugin's sensitive
fields (apiKey, tokens, ports, etc.) under plugins.entries.<id>.config.

Config key mapping per plugin is derived from each plugin's
openclaw.plugin.json configSchema. .env.example updated with all
available variables and their corresponding plugin IDs.

.env.example

@@ -1,18 +1,35 @@
 # HangmanLab.Server.T2 — Plugin Configuration
 # Copy to .env and fill in values. This file is gitignored.
+# Values are written to openclaw config via 'openclaw config set'.
 
 # ── OpenClaw ─────────────────────────────────────────────────────────────────
 OPENCLAW_PATH=~/.openclaw
 
-# ── HarborForge Plugin ───────────────────────────────────────────────────────
+# ── HarborForge Plugin (harbor-forge) ────────────────────────────────────────
 HF_BACKEND_URL=https://hf-api.hangman-lab.top
 HF_API_KEY=
 HF_MONITOR_IDENTIFIER=
+HF_MONITOR_PORT=
+HF_REPORT_INTERVAL=30
+HF_CALENDAR_API_KEY=
 
-# ── Yonexus.Server ───────────────────────────────────────────────────────────
-YONEXUS_PORT=18900
-YONEXUS_SECRET=
-
-# ── ContractorAgent ──────────────────────────────────────────────────────────
+# ── ContractorAgent (contractor-agent) ───────────────────────────────────────
 CONTRACTOR_BRIDGE_PORT=18800
 CONTRACTOR_BRIDGE_API_KEY=
+
+# ── Dirigent (dirigent) ──────────────────────────────────────────────────────
+DIRIGENT_MODERATOR_BOT_TOKEN=
+DIRIGENT_SIDECAR_PORT=
+DIRIGENT_NO_REPLY_PROVIDER=
+DIRIGENT_NO_REPLY_MODEL=
+DIRIGENT_SCHEDULE_IDENTIFIER=
+
+# ── PaddedCell (padded-cell) ─────────────────────────────────────────────────
+PADDEDCELL_SECRET_MGR_PATH=
+PADDEDCELL_OPENCLAW_PATH=
+
+# ── Yonexus.Server (yonexus-server) ──────────────────────────────────────────
+YONEXUS_PORT=18900
+YONEXUS_NOTIFY_BOT_TOKEN=
+YONEXUS_ADMIN_USER_ID=
+YONEXUS_PUBLIC_WS_URL=