feat(claude): shared account budget in Team tab + meta-sidebar card facelift (T-158)

Implements T-158 option A: the forwarded /usage budget (already parsed for
the Activity tab, T-415) now also renders in the Team tab as a single
ACCOUNT card, captioned "shared across the team". Usage is per-account —
every team session shares one ~/.claude login — so it's shown once, not
split per member (which would just repeat identical numbers).

Facelift: the Activity, Team, and Config tabs now render their sections as
elevated cards (panelHeader fill, dividerColor hairline, 6px radius) under
small-caps mono headers, matching the settings overlay's card design
(settings_category_view). Shared helpers — metaSectionHeader / metaCard /
metaCardRow — live in meta_sidebar/models.dart; the SESSION control strip
and the pinned Config SETTINGS block adopt the same card. The shared
ClideAccordion (also used by decisions/tickets) is left untouched.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

assets/i18n/en_us/builtin.claude.json

@@ -194,6 +194,8 @@
   "taskRow.reassign": { "translation": "Reassign task" },
   "team.empty": { "translation": "No team active." },
   "team.section.tasks": { "translation": "TASKS" },
+  "team.section.usage": { "translation": "Account" },
+  "team.usage.shared": { "translation": "Shared across the team" },
   "tabStrip.activity": { "translation": "Activity" },
   "tabStrip.team": { "translation": "Team" },
   "tabStrip.team.count": { "translation": "Team · {count}" },

assets/i18n/nl_nl/builtin.claude.json

@@ -194,6 +194,8 @@
   "taskRow.reassign": { "translation": "Taak opnieuw toewijzen" },
   "team.empty": { "translation": "Geen team actief." },
   "team.section.tasks": { "translation": "TAKEN" },
+  "team.section.usage": { "translation": "Account" },
+  "team.usage.shared": { "translation": "Gedeeld met het hele team" },
   "tabStrip.activity": { "translation": "Activiteit" },
   "tabStrip.team": { "translation": "Team" },
   "tabStrip.team.count": { "translation": "Team · {count}" },