docs(drivers): Wave 0-2 tracking doc + Wave 1/2 implementation plans

Add a living progress tracker (docs/plans/2026-07-24-driver-expansion-tracking.md)
for the driver-expansion program's Waves 0-2, linked from the program design doc's
document map. One row per deliverable pointing at design + implementation plan + status.

Add executable implementation plans (plan .md + co-located .tasks.json) for the four
Wave 1/2 drivers, each authored by writing-plans methodology off its design doc and
mirroring the relevant existing driver:

- Modbus RTU        11 tasks  (extends Driver.Modbus; RTU-over-TCP, direct-serial descoped)
- SQL poll          22 tasks  (ISqlDialect seam, SQL Server only in v1; SQLite + central-SQL fixtures)
- MTConnect Agent   23 tasks  (browse free via Wave-0 seam; TrakHound-vs-hand-rolled = Task 0)
- MQTT/Sparkplug B  27 tasks  (P1 plain MQTT 0-14 then P2 Sparkplug 15-26; MQTTnet-5 pinning spike = Task 0)

Wave 0 (universal browser) remains merged (056887d6) with its live gate open (#468).
All four new plans are design-only -> plan-ready; nothing built yet.

Claude-Session: https://claude.ai/code/session_01GASWkNEi68FSCtvr6rLoEW

docs/plans/2026-07-15-driver-expansion-program-design.md

@@ -26,7 +26,9 @@ OpcUaClient, Historian.Gateway (`src/Drivers/`).
 
 ## 2. Document map
 
-**Program:** this file.
+**Program:** this file (architecture / shared contract / build order).
+**Progress tracker (Waves 0–2):** [`2026-07-24-driver-expansion-tracking.md`](2026-07-24-driver-expansion-tracking.md)
+— per-deliverable status + links to each design doc and implementation plan.
 
 **Research reports** (`docs/research/drivers/`, index: [`README.md`](../research/drivers/README.md)):
 - [`mtconnect-agent.md`](../research/drivers/mtconnect-agent.md) ·