Realign processor stream-name default to telemetry:teltonika

Stage discovered the wrong default at runtime: tcp-ingestion's compiled
default REDIS_TELEMETRY_STREAM is 'telemetry:teltonika' but processor's
was 'telemetry:t', so the two services were talking past each other —
tcp-ingestion publishing to one stream, processor reading another empty
one. The deploy stack now pins both to the same value via a shared env
var, but the processor's compiled default should also match so local
development and the integration test stay aligned with reality.

Changes:
- src/config/load.ts — default changed to 'telemetry:teltonika'
- .env.example — same
- test/config.test.ts — default-value assertion updated
- planning docs (ROADMAP, phase-1 README, tasks 03/08/10, phase-3 README) —
  occurrences of 'telemetry:t' replaced with 'telemetry:teltonika'

The deploy stack remains the single source of truth via the shared
REDIS_TELEMETRY_STREAM env var. Compiled defaults are belt-and-braces.

.planning/phase-1-throughput/03-config-and-logging.md

@@ -30,7 +30,7 @@ Validate environment variables on startup with `zod`, build the pino root logger
 | `LOG_LEVEL` | no | `info` | `trace` / `debug` / `info` / `warn` / `error` |
 | `REDIS_URL` | yes | — | e.g. `redis://redis:6379` |
 | `POSTGRES_URL` | yes | — | e.g. `postgres://user:pass@db:5432/trm` |
-| `REDIS_TELEMETRY_STREAM` | no | `telemetry:t` | Must match `tcp-ingestion`'s `REDIS_TELEMETRY_STREAM` |
+| `REDIS_TELEMETRY_STREAM` | no | `telemetry:teltonika` | Must match `tcp-ingestion`'s `REDIS_TELEMETRY_STREAM`. Pinned via the deploy-stack shared env var so the two services cannot drift from each other. |
 | `REDIS_CONSUMER_GROUP` | no | `processor` | All Processor instances join this group |
 | `REDIS_CONSUMER_NAME` | no | `${INSTANCE_ID}` | Unique per instance — defaults to instance id |
 | `METRICS_PORT` | no | `9090` | HTTP server port for `/metrics`, `/healthz`, `/readyz` |