fix(client): contain notification-callback failures and document the source lifecycle

Review follow-ups: the three new notify loops (currentProvideInfo
subscribers, ui-skill lexicon listeners, late-registration controller
setup) now contain per-callback failures so one faulty consumer cannot
starve the rest, abort the list projection pass, or poison the source
roster with no disposer; controller lexicon polling drops a throwing
source with a console record like the candidate path. The ui-slash
README (both languages) now states the late-registration warm and the
subscribeLexicon contract, and the scenario suite drives a typed /name
token gaining its decoration when the roll settles with no further
input.

packages/client/ui-slash/README.i18n.yaml

@@ -1,6 +1,6 @@
 # Bilingual-pair consistency record (docs/i18n/README.md): the git blob hash of each
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
-#   pnpm run verify-translation-pairing --write
-README.md: d2978695d71686059bfbcbb4fc3ef896d92add4a
-README.zh.md: 6aeb078a922aaa93d50ed16b4dbe54329737d018
+#   pnpm run verify-translation-pairing --write packages/client/ui-slash/README.md
+README.md: 4e363c2682bf91862ec40f3f2174831451fb9b0d
+README.zh.md: 76d39673cb853d1889ee84cb9f3595708eae2db3