Let a session resume itself when its usage limit lifts

Off by default and per session: it spends quota the moment quota exists,
with nobody watching, which is not a thing a default may decide. Switched
on from the session settings dialog, with the message it sends editable
("continue" unless something else is typed).

Running out of quota becomes a state rather than an error. The Claude
driver recognises its dialect's sentence -- `Claude AI usage limit
reached|1788546972` -- and reports `LimitReached` with the reset time it
gave; nothing above a driver matches on a string. The transcript draws it
as a divider, like a clear or a compaction.

The schedule is a plan to *ask*, never a plan to send. Both reset times
available are untrustworthy in the direction that matters -- the dialect's
is written when the turn fails, the endpoint's moves when the window does
-- so the wait ends in a question to the usage meter, and only `ok` with
no window at 100% sends anything. A window still spent reschedules to its
own reset time, which is what makes a limit that lifts late wait longer
and one that lifts early resume sooner. A meter that cannot be asked is a
longer wait too, never a send. A day after the limit was hit the wait
gives up and says so in the transcript, so a machine that can never be
asked is not retried for ever.

The schedule is persisted on the session: a five-hour window outlasts a
backend restart, and a wait forgotten across one never comes back.

Driven end to end with echo, never a real account: `/limit [minutes]`
reports the same event a real driver does and `/usage` sets what the meter
answers, deliberately separate so the two can disagree. The wait moved
from the dialect's two minutes to the meter's seven when the meter changed
its mind, and the message went out on the first check after the meter came
back under the limit.

Also makes the settings dialog scrollable, which these two controls made
necessary: at a 1.5x system font it clipped the last of them with nothing
on screen to say so.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

app/androidApp/src/main/kotlin/com/example/aiapp/Dividers.kt

@@ -12,6 +12,10 @@ import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.unit.dp
+import java.time.Instant
+import java.time.ZoneId
+import java.time.format.DateTimeFormatter
+import java.time.format.FormatStyle
 
 /**
  * A line across the transcript saying what left the session's context.
@@ -47,3 +51,40 @@ fun TranscriptDivider(text: String, color: Color, modifier: Modifier = Modifier)
 fun ClearedRow(modifier: Modifier = Modifier) {
     TranscriptDivider("Context cleared", clearedColor, modifier)
 }
+
+/**
+ * The mark running out of quota leaves.
+ *
+ * The same red the usage bar takes when a window is spent, because it is the same fact in a second
+ * place: colour by consequence, so "there is nothing left to spend" is learned once.
+ *
+ * A time rather than a countdown. The row is folded once and never re-measured, so a span would go
+ * stale on screen the moment it was drawn; and this is when the *account* said it would reset,
+ * which is not a promise about when the session picks back up. A limit the session was told no
+ * reset time for says nothing about one -- that state has its own words rather than a plausible
+ * number.
+ */
+@Composable
+fun LimitRow(item: TranscriptItem.LimitNote, modifier: Modifier = Modifier) {
+    TranscriptDivider(limitSummary(item.resetsAt, ZoneId.systemDefault()), overLimitColor, modifier)
+}
+
+/**
+ * What the row says. Split out so the wording is testable without a screen, since the two states it
+ * has to keep apart -- a reset time that arrived and one that never did -- are exactly the pair
+ * that reads the same when it goes wrong.
+ *
+ * [zone] is a parameter rather than read here so a test says the same thing wherever it runs.
+ */
+fun limitSummary(resetsAt: Double?, zone: ZoneId): String {
+    val at = resetsAt?.let {
+        try {
+            DateTimeFormatter.ofLocalizedTime(FormatStyle.SHORT)
+                .withZone(zone)
+                .format(Instant.ofEpochSecond(it.toLong()))
+        } catch (_: Exception) {
+            null
+        }
+    }
+    return if (at == null) "Usage limit reached" else "Usage limit reached • resets $at"
+}