orpc-v2: migrate _template scaffold to the new plugin API

[elliotBraem]

Ticket ID: B4a

Parent

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

What to build

Stage B, step 4a: migrate the _template scaffold to the new createPlugin API — Layer-based initialize, no tools/buildService, no context-bridge module. This scaffold is the reference for every future child-repo plugin (bos init), so it must read as the canonical example of the new pattern, including the scaffold's self-documentation.

Acceptance criteria

• Template's integration tests green on the new API
• Scaffold builds via its rspack config; no old-API remnants (tools, context bridge)
• A bos init-generated scratch child using the scaffold compiles against the branch's every-plugin

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