#853 Epic #847 · Unit 1: Land the ClickHouse projection foundation (schema + init SQL + compose service)

Part of epic #847 (monotonic-ledger scoring rework + ClickHouse-first projections). This is Unit 1 of 6 and the prerequisite for the rest of the epic — no projection or grant-streaming unit can land until the ClickHouse serving layer exists in-tree.

Problem

services/telemetry/lib/consumers/clickhouse.ts already streams the raw event firehose into a flat swamp.events table in near-real-time (~2s poll, per-watcher-batch insert), but:

• The init schema its own comment references (infrastructure/clickhouse/init/01-schema.sql) does not exist in the repo.
• There are ZERO materialized views or aggregating engines.
• There is NO read path back into the app.
• The CH engine/schema work currently lives on an unmerged branch.

Scope

1. Land/merge the unmerged ClickHouse foundation branch. First task: read the branch and document exactly what it contains before merging.
2. Add infrastructure/clickhouse/init/01-schema.sql defining swamp.events (and the MATERIALIZED dimension columns the consumer comment references).
3. Add a ClickHouse service to docker-compose.yml so the local stack boots CH alongside Mongo / LocalStack / telemetry.
4. Confirm ClickHouseConsumer registration (services/telemetry/main.ts, gated on CLICKHOUSE_URL) works end-to-end against the composed service.

Out of scope

• The score_grants table and any score materialized views (Units 4–5).
• Any app read path (Unit 5).

Acceptance

• ClickHouse boots in docker compose up -d.
• An event POSTed to /ingest lands as a row in swamp.events (smoke test).
• infrastructure/clickhouse/init/01-schema.sql exists and is applied on CH init.
• No change to the Mongo scoring path.