memory: canonicalise habit keys, take the median on a clock, name the period

Three defects in how the counted profile is read back.

The counting unit was the key the LLM invented. There is no allowlist and no
normalization behind it, so "я выпил воду" and "попил воды" landed as different
keys, split one habit into two, and dropped both below the two-day threshold.
Keys now go through an alias table in behavior_ru.json before they are counted.
An unglossed key is quoted rather than recited as a verb, because "обычно ты
выпил_воды около 09:00" is not a sentence.

The typical time was a median of minutes since midnight, which is wrong for
anything that straddles midnight. Bedtimes of 23:40, 23:50, 00:10 and 00:20
gave 12:00, on the one activity most likely to cross the boundary. It is now a
circular median, and when the observations span more than half the clock she
names the habit without a time instead of inventing one.

The rest is wording. Profile.Since was computed and never spoken, so "обычно"
was an unfalsifiable claim; the overall read-back now says over how many days
of records it holds. The no-data weekday answer said "у меня пока нет ничего
постоянного" about a question concerning him. And "quiet" was a bare prefix in
the non-behavioural list, so any future self-fact key starting with those five
letters would have been dropped.

Found in review of #59.

internal/memory/behavior_ru.go

@@ -22,15 +22,18 @@ import (
 var behaviorRUJSON []byte
 
 type behaviorRU struct {
-	Weekdays   []string          `json:"weekdays"`
-	Activities map[string]string `json:"activities"`
+	Weekdays   []string            `json:"weekdays"`
+	Activities map[string]string   `json:"activities"`
+	KeyAliases map[string][]string `json:"key_aliases"`
 }
 
 var (
 	// weekdayRU — dative plural, indexed by time.Weekday.
 	weekdayRU []string
-	// activityRU — fact key to second-person-singular verb phrase.
+	// activityRU — canonical fact key to second-person-singular verb phrase.
 	activityRU map[string]string
+	// canonicalKey — observed fact key to the canonical key it counts as.
+	canonicalKey map[string]string
 )
 
 func init() {
@@ -42,4 +45,11 @@ func init() {
 		panic(fmt.Sprintf("memory: behavior_ru.json: want 7 weekdays, got %d", len(v.Weekdays)))
 	}
 	weekdayRU, activityRU = v.Weekdays, v.Activities
+	canonicalKey = make(map[string]string)
+	for canonical, variants := range v.KeyAliases {
+		canonicalKey[canonical] = canonical
+		for _, variant := range variants {
+			canonicalKey[variant] = canonical
+		}
+	}
 }