docs: simplify jt808 mileage runtime state

docs/target-architecture.md

@@ -32,8 +32,7 @@ is explicitly deployed.
 - Store complete raw payload metadata and parsed JSON in TDengine `raw_frames`.
 - Store query-friendly location rows separately from raw payload JSON.
 - Keep derived statistics in metric tables, not protocol-specific daily tables.
-- Use Redis only for hot state or streaming calculation state that can be
-  rebuilt from Kafka.
+- Use Redis only for optional latest-state APIs that can be rebuilt from Kafka.
 - Keep optional compatibility modules outside the production hot path.
 
 ## Non-Goals
@@ -133,9 +132,8 @@ calculation_method = JT808_TOTAL_MILEAGE_DIFF
   mileage used for the subtraction stay on the same metric row as calculation
   source columns.
 
-There is no JT808-specific daily mileage table and no in-memory production
-state-store mode. Restart recovery reads the same metric row, so it does not
-require a separate Redis mileage state.
+Runtime state: none outside `vehicle_stat_metric`. There is no JT808-specific
+daily mileage table. Restart recovery reads the same metric row.
 
 ### Latest State
 
@@ -196,6 +194,5 @@ flowchart LR
 - Location queries page over compact rows and reference raw records instead of
   duplicating full raw JSON.
 - JT808 daily mileage is stored only in `vehicle_stat_metric`.
-- Runtime state needed for 808 mileage is also in `vehicle_stat_metric`, with no
-  Redis or production memory state-store mode.
+- Runtime state needed for 808 mileage is also in `vehicle_stat_metric`.
 - Build validation covers the active modules and their composition tests.