praxis: an empty attention list is not always an all-clear (V-540)

ECOSYSTEM-SPEC §2.6 requires list_attention to distinguish "nothing needs
attention" from "I cannot currently tell", and to say so when a source is
failed or stale. Maven said the first one unconditionally: ListAttention
decoded into []map[string]any, the word degraded appeared nowhere, and an empty
list answered "ничего не требует внимания". A Praxis with every source dead
read as calm.

Two halves, because the spec's mechanism does not exist server-side yet. The
deployed Praxis answers /api/v1/tools/attention with a bare array and no
envelope, so praxisAttention now decodes either shape and believes a degraded
array when one arrives. Until one does, an empty list triggers one read of
/api/v1/sources, and anything that is not reporting health "ok" is named
instead of the all-clear. Zero sources is the same answer: a Praxis that polls
nothing knows nothing, which is the state of this box today.

A sources read that fails is deliberately not a hedge. The attention call
succeeded, and not being able to ask about health is not evidence of a fault.

Both hedges also cover the entity-scoped digest, where a per-entity all-clear
is the more convincing of the two. New keys attention_degraded and
attention_no_sources, in acts_ru_v1.json and the floor. The fake Praxis serves
one healthy source by default, so the existing attention tests still assert an
all-clear on purpose rather than by omission.

internal/phraser/acts.go

@@ -60,13 +60,17 @@ const (
 	AttentionNoneEntity = "attention_none_entity"
 	AttentionListEntity = "attention_list_entity"
 	AttentionFailEntity = "attention_fail_entity"
-	ChangesNone         = "changes_none"
-	ChangesList         = "changes_list"
-	ChangesFail         = "changes_fail"
-	HomeUnreachable     = "home_unreachable"
-	HomeEmpty           = "home_empty"
-	HomeOn              = "home_on"
-	HomeDark            = "home_dark"
+	// AttentionDegraded and AttentionNoSources — the two ways an empty
+	// attention list is not an all-clear (ECOSYSTEM-SPEC §2.6, Vikunja #540).
+	AttentionDegraded  = "attention_degraded"
+	AttentionNoSources = "attention_no_sources"
+	ChangesNone        = "changes_none"
+	ChangesList        = "changes_list"
+	ChangesFail        = "changes_fail"
+	HomeUnreachable    = "home_unreachable"
+	HomeEmpty          = "home_empty"
+	HomeOn             = "home_on"
+	HomeDark           = "home_dark"
 )
 
 var actKeys = []string{
@@ -76,6 +80,7 @@ var actKeys = []string{
 	EcoDenied, EcoDown, EcoAmbiguous, EcoUnknownEntity, EcoNoNexus, EcoAboutWhat, EcoRecall,
 	AttentionNone, AttentionList, AttentionFail,
 	AttentionNoneEntity, AttentionListEntity, AttentionFailEntity,
+	AttentionDegraded, AttentionNoSources,
 	ChangesNone, ChangesList, ChangesFail,
 	HomeUnreachable, HomeEmpty, HomeOn, HomeDark,
 }
@@ -113,6 +118,8 @@ var actFloor = map[string]string{
 	AttentionNoneEntity: "по «{name}» ничего нет.",
 	AttentionListEntity: "по «{name}»: {items}",
 	AttentionFailEntity: "не могу сейчас узнать, что требует внимания по «{name}».",
+	AttentionDegraded:   "за всё не отвечу — источники молчат: {items}.",
+	AttentionNoSources:  "мне пока нечего смотреть — у Praxis нет источников.",
 	ChangesNone:         "изменений нет.",
 	ChangesList:         "изменения: {items}",
 	ChangesFail:         "не могу сейчас узнать об изменениях.",

internal/phraser/acts_ru_v1.json

@@ -114,6 +114,14 @@
       "fixed": true,
       "variants": ["не могу сейчас узнать, что требует внимания по «{name}»."]
     },
+    "attention_degraded": {
+      "fixed": true,
+      "variants": ["за всё не отвечу — источники молчат: {items}."]
+    },
+    "attention_no_sources": {
+      "fixed": true,
+      "variants": ["мне пока нечего смотреть — у Praxis нет источников."]
+    },
     "changes_none": {
       "fixed": true,
       "variants": ["изменений нет."]