Correct Goal 7 documentation for kDisco-based speed control (#494)

* docs: correct Goal 7 speed control notes
* docs: mark Goal 7 complete

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Bedrich Hovorka <bedrich.hovorka@gmail.com>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: 3 people

LONG_TERM_GOALS.md

@@ -209,6 +209,7 @@ Users can automatically collect key performance indicators during simulation inc
 **Category:** I: System Operations
 **Priority:** Critical
 **Development Estimate:** 1 month
+**Status:** ✅ COMPLETE
 
 **User Value:**
 Users can adjust simulation speed from slow motion (for detailed observation) to fast forward (for quick scenario completion). This provides flexibility for different use cases: slow for education, fast for research batch runs.
@@ -222,7 +223,9 @@ Users can adjust simulation speed from slow motion (for detailed observation) to
 **Dependencies:** None (quick win)
 
 **Implementation Notes:**
-- kDisco already supports speed control; needs UI exposure
+- The simulation library interface used by the model (historically jDisco, now kDisco/KMP) runs in pure simulation time and has no native wall-clock speed control or synchronization.
+- Speed control for `ShuntingLoop` is implemented via the `RealTimeSynch` inner process inside `sim/ShuntingLoop.kt` (enabled by `enableRealTimeSync`, paced by `speedMultiplier`). This resides in the `sim/` package.
+- `SimulationRunner` provides a complementary external throttling API (`throttle()`, `awaitIfPaused()`) callable from the simulation thread; this is the designed extension point for future simulation processes that delegate pacing outside the `sim/` package.
 - Quick win - implement early for immediate value
 
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