Docs + simulations refresh; align spill-flow keys with new position

- wiki/functional-description.md: rename Overfill Protection → High-volume
  Safety; tighten basin-ordering chain; relocate level-based mode
  diagrams under wiki/diagrams/modes/level-based/; document the new
  flow.predicted.overflow.default position (replaces the previous
  child='overflow' under position 'out'); add underflowVolume +
  predictedUnderflowVolume entries.
- wiki/modes/{levelbased,powerbased}.md: paragraph cleanups.
- wiki/diagrams: move level-linear basin diagram under modes/level-based/
  alongside a new level-log variant.
- simulations/run.js: add max_demand_gt expectation.
- simulations/scenarios/*: minor fixture updates.
- test/basic/nodeClass-config.test.js: new config-shape coverage.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

wiki/diagrams/README.md

@@ -51,9 +51,10 @@ Use a descriptive `alt` text; it's the fallback if the SVG fails and it shows up
 | Diagram | Shows |
 |---|---|
 | `basin-model` | Shared physical basin cross-section — walls, pipe reference heights, derived safety zones, storage/dead volumes |
-| `modes/basin-mode-level-linear` | Level-linear control mode — `startLevel`, demand ramp, threshold-shift behaviour |
+| `modes/level-based/basin-mode-level-linear` | Level-based linear control curve — rising ramp starts at inlet level, falling ramp shifts to `startLevel` |
+| `modes/level-based/basin-mode-level-log` | Level-based logarithmic control curve — fast early response, falling ramp shifts to `startLevel` |
 | `control-zones` | Legacy vertical level axis ("thermometer") for `levelbased` mode — STOP / DEAD ZONE / RUN with demand ramp |
-| `safety-rules` | Dry-run vs overfill rule asymmetry — which children stop, which keep running |
+| `safety-rules` | Dry-run vs high-volume safety rule asymmetry — which children stop, which keep running |
 
 ## Making a brand-new diagram