improvement: FDI tooth chart overhauled.

AGENTS.md

@@ -46,7 +46,7 @@ frontend/src/
 - Day/mode gate: editable only for live draft on today/future (`canEditTreatmentForDay`). Past day / historical load → read-only form.
 - Sent-to-lab detail locks that line; **Add detail** still OK same day; **Remove detail** = trash icon on each detail chip (not in the wizard Content step) — only unsent and not the last line. Attachment upload blocked when sent (`TREATMENT_DETAIL_SENT`).
 - **Entry wizard:** `WizardStepper` — Teeth → Content → Lab; Lab step only when active detail type is lab-dependent (prosthesis); entering Lab auto-opens shipment draft (no Add-shipment CTA). Content notes field label is **Notes** (clinical). Detail chips ≠ wizard chrome. Switching detail chips resets wizard to Teeth unless `pendingEntryStepRef` requests Lab (e.g. opening a case from the lab shipments rail).
-- **Tooth selection:** Shift+click same-arch range = connected bridge (one lab row); overlapping Shift bridges merge by union. Plain click add/remove singles; click in a bridge cuts that tooth out as a selected single (ends keep one bridge; middle splits into two). Never a 1-tooth connected (no lone dots). Helpers: `toothSelectionGroups.ts`. Connected label: `ConnectedSelectionBadge`. After send, Cases/Tasks merge teeth by prosthesis type.
+- **Tooth selection:** Neighbor empty/filled circles between selected adjacent teeth connect/disconnect bridges; Shift+range selects only (empty circles; overlap absorbs as singles); midline 11–21 / 41–31 allowed. Plain click selects/deselects (deselect splits bridges). Never a 1-tooth connected. Helpers: `toothSelectionGroups.ts`. Connected label: `ConnectedSelectionBadge`. After send, Cases/Tasks merge teeth by prosthesis type.
 - **Lab dispatch layout:** due date beside title (`justify-between`, logical start/end for RTL); prosthesis type on same row as teeth from `md:` up (stacked on mobile).
 
 **Treatment lab rules (quick ref):**