orpc-v2: migrate proposals plugin to the new plugin API (publisher rename)

[elliotBraem]

Ticket ID: B4d

Parent

#248 — orpc-v2: consolidate fork into everything-dev and migrate platform to oRPC v2 + Effect 4 (epic)

What to build

Stage B, step 4d: migrate the proposals plugin to the new createPlugin API, including its background publisher loops on the renamed @orpc/publisher: publish() is now async (loops must await), and resumeRetentionSeconds becomes resume: { enabled, seconds }. Restart-resume behavior of in-flight publications must be preserved.

Acceptance criteria

• Proposals plugin test suite green on the new API
• Publisher loops await publish correctly; resume-after-restart behavior verified

Blocked by

• orpc-v2: createPlugin restructure (Layer-based initialize, errorStatusMap, scope lifecycle) #259 — createPlugin restructure
• orpc-v2: migrate all six contracts to the v2 route builder #260 — migrate all six contracts to the v2 route builder