fix(medications): silence a switched-off module and an ended course

With the Medications module switched off, dose reminders, missed-dose
rows and low-stock alerts kept coming, a tap on one landed on
"Medications is switched off", and the Telegram buttons still booked
intakes. The reminder tick now drops the medications of an owner with the
module off, one module read per owner and tick, so neither a reminder nor
a missed-dose placeholder is written while it is off. The low-stock pass
skips such a user, as the mood reminder does for its module, and the bot
offers and books nothing.

A medication whose course had ended still counted as live: the low-stock
pass kept warning about its stock, and the bot's /add list offered it and
booked a dose after the end, taking a unit off the stock. The low-stock
pass and every bot path now skip a course that has ended on the person's
clock. A course that has not started yet keeps its reorder warning and
stays in the bot. A paused medication is already active: false, so the
existing filter keeps it out.

The bot's six copies of the medication lookup go through one helper.

src/__tests__/baselines/source-function-lines.json

@@ -339,8 +339,8 @@
     "lib/support/report.ts :: collectSupportReportFacts": 332,
     "lib/targets/build-response.ts :: buildTargetsResponse": 330,
     "lib/targets/vitals-builder.ts :: buildVitalTargets": 324,
-    "lib/telegram-webhook-handlers.ts :: handleCallback": 599,
-    "lib/telegram-webhook-handlers.ts :: handleTextMessage": 337,
+    "lib/telegram-webhook-handlers.ts :: handleCallback": 582,
+    "lib/telegram-webhook-handlers.ts :: handleTextMessage": 322,
     "lib/withings/sync-activity.ts :: syncUserActivity": 377,
     "lib/withings/sync-ecg.ts :: syncUserEcg": 202,
     "lib/withings/sync-sleep.ts :: syncUserSleep": 414,