fix: component port labels showing wrong name after editing blueprint

The label lookup in drawComponentGate read from gate.component (potentially
stale copy) while gateOutputCount read from state.customComponents (updated
definition), causing a mismatch — fewer ports but old outputIds, so the
first (deleted) output's label was shown instead of the surviving one.

Three fixes:
- renderer: use customComponents as authoritative source for label lookup
- saveLoad: re-link gate.component refs to customComponents after loading
- components: update existing instances even when a "new" component
  overwrites an existing definition with the same name

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

js/components.js

@@ -285,12 +285,15 @@ export function exitComponentEditor(name, shouldSave) {
         // Save the component (works for both new and edited)
         const result = saveComponentFromCircuit(name);
 
-        // If editing an existing component, update all placed instances in the main circuit
-        if (editingId && result.success && state.savedMainCircuit) {
+        // Update all placed instances of this component in the main circuit.
+        // Handles both: editing existing component (editingId matches) AND
+        // creating a "new" component that overwrites an existing one (same sanitized name).
+        if (result.success && state.savedMainCircuit) {
             const updatedComp = state.customComponents[result.component.id];
             if (updatedComp) {
+                const matchId = editingId || result.component.id;
                 for (const gate of state.savedMainCircuit.gates) {
-                    if (gate.component && gate.component.id === editingId) {
+                    if (gate.component && gate.component.id === matchId) {
                         gate.component = updatedComp;
                         // Clear persisted internal state so it re-initializes from updated blueprint
                         delete gate._internalGates;