Add README and env.example for multi-task examples

Adapts the pipecat-subagents `examples/README.md` to the new
layout (`multi-task/` umbrella, `local-handoff/`, `distributed-handoff/`,
`remote-proxy-assistant/`, `parallel-debate/`, `code-assistant/`),
updates the agent→task / job-RPC vocabulary, drops the
single-agent and llm-and-flows examples (gone in the port), and
adds a new section for the PGMQ handoff transport.

examples/multi-task/env.example

@@ -0,0 +1,22 @@
+# Audio services
+DEEPGRAM_API_KEY=
+CARTESIA_API_KEY=
+
+# LLM
+OPENAI_API_KEY=
+
+# Voice code assistant (Claude Agent SDK)
+ANTHROPIC_API_KEY=
+
+# Transport (optional — only needed with --transport daily)
+DAILY_API_KEY=
+
+# Distributed handoff via PGMQ
+# Get from: Supabase dashboard > Project Settings > Database > Connection string
+# The session-mode pooler (port 5432) is preferred. The transaction-mode
+# pooler (port 6543) also works but logs benign "resetting connection"
+# warnings.
+# Format (session pooler):
+#   postgresql://postgres.<project-ref>:<password>@aws-0-<region>.pooler.supabase.com:5432/postgres
+DATABASE_URL=
+PGMQ_CHANNEL=pipecat_acme