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.

.env.example

@@ -22,7 +22,9 @@ REDIS_URL=redis://localhost:6379
 POSTGRES_URL=postgres://postgres:postgres@localhost:5432/trm
 
 # Redis Stream name to consume from. Must match tcp-ingestion's REDIS_TELEMETRY_STREAM.
-REDIS_TELEMETRY_STREAM=telemetry:t
+# In the deploy stack this is pinned via the shared REDIS_TELEMETRY_STREAM env
+# var so neither service can drift from the other.
+REDIS_TELEMETRY_STREAM=telemetry:teltonika
 
 # Redis consumer group name. All Processor instances join this group.
 REDIS_CONSUMER_GROUP=processor