Inference-depth anchoring playground: vertical + radial modes

The graph's follows/supports edges encode derivation (premise ->
conclusion); the layout can now express that rank spatially, as a
session-only playground toggle (nothing promoted yet):

- inferenceDepths: longest chain from a base node, CYCLE-SAFE by
  SCC condensation (Tarjan, iterative) — the DAG property is typical,
  not guaranteed; cycle members share their component's depth (mutual
  support = equal footing). O(V+E), pure, deterministic.
- DepthAnchor force: per-node target scalar — vertical mode rows
  (baseline at the anchor centroid, arrows up), radial mode rings
  (foundations center, outer boundary = edge of knowledge). The rank
  is computed, not simulated: pairwise up-forces can't give baselines.
- Mode projections: gravity x-only in vertical / dropped in radial;
  cluster pull x-only in vertical / tangential-only in radial; the
  anchor re-blend preserves user arrangement in the FREE dimension
  only (x / angle) — meaning owns the constrained axis, memory owns
  the free one.
- setPhysicsTuning reheats (alpha 1): toggling a mode re-forms the
  graph live and commits the new rest state; drag release is springy
  along the constrained axis (node returns toward its level/ring).
- Sweep on the real graph: strength 0.8 = 215/216 arrows correct with
  organic sag; 1.5 = crisp rows. 174 base nodes, max chain depth 7,
  zero cycles in current data. replay-layout --depth=<mode> bakes a
  mode into the ledger for rest-state experiments.

components/graph-view.tsx

@@ -665,6 +665,41 @@ export function GraphView() {
 							<span className="text-[10px] font-medium uppercase tracking-wide text-muted-foreground">
 								Physics
 							</span>
+							<label className="flex items-center justify-between gap-2 text-xs">
+								Depth anchor
+								<select
+									className="rounded border bg-background px-1 py-0.5 text-xs"
+									value={physicsTuning.depthMode}
+									onChange={(e) =>
+										setPhysicsTuning((t) => ({
+											...t,
+											depthMode: e.target.value as PhysicsTuning["depthMode"],
+										}))
+									}
+								>
+									<option value="off">Off</option>
+									<option value="vertical">Vertical (up)</option>
+									<option value="radial">Radial (outward)</option>
+								</select>
+							</label>
+							<NumberField
+								label="Depth strength"
+								value={physicsTuning.depthStrength}
+								step={0.05}
+								onChange={(v) => setPhysicsTuning((t) => ({ ...t, depthStrength: v }))}
+							/>
+							<NumberField
+								label="Depth spacing"
+								value={physicsTuning.depthSpacing}
+								step={10}
+								onChange={(v) => setPhysicsTuning((t) => ({ ...t, depthSpacing: v }))}
+							/>
+							<NumberField
+								label="Base ring radius"
+								value={physicsTuning.depthBaseRadius}
+								step={20}
+								onChange={(v) => setPhysicsTuning((t) => ({ ...t, depthBaseRadius: v }))}
+							/>
 							<NumberField
 								label="Node repulsion"
 								value={physicsTuning.chargeStrength}