Fix missing Trio FPU entries

[aug0211]

• LoopFollow was deduplicating Nightscout treatments by Trio's shared FPU ID, which hid the first scheduled entry from the graph
• Deduplicate by event type and occurrence time as well, preserving distinct FPU entries while still collapsing true duplicates

[bjorkert]

Verified against Trio's uploader: FPU siblings are uploaded with the shared fpuID as id and only created_at (Trio's NightscoutTreatment has no timestamp field), with entries spaced by the minute interval (min 10), so the occurrence key always splits siblings correctly. Ran the suite plus a simulator A/B against mock Nightscout data: dev collapsed 5 siblings to one dot (carbs today 32), with this fix all 5 render (40) and true duplicates (same id, same created_at, different _id) still collapse — the #569 behavior is preserved.