MUL-2797 feat(agent): add Claude Opus 4.8 to model catalog & pricing

Claude Code now ships Opus 4.8 (claude-opus-4-8). Add it to the three
places that enumerate Claude models so the picker, thinking-level
catalog, and usage cost estimates all recognize it:

- claudeStaticModels(): list Claude Opus 4.8 (Sonnet 4.6 stays default)
- claudeModelEffortAllow: Opus supports the full low..max set incl. xhigh
- MODEL_PRICING: $5/$25 in, $0.50 cache read, $6.25 5m cache write —
  same current-gen Opus tier as 4.5/4.6/4.7, confirmed against
  platform.claude.com/docs/en/about-claude/pricing

Co-authored-by: multica-agent <github@multica.ai>

packages/views/runtimes/utils.ts

@@ -158,6 +158,7 @@ const MODEL_PRICING: Record<
   "claude-opus-4-5":    { input: 5,    output: 25,   cacheRead: 0.50, cacheWrite: 6.25 },
   "claude-opus-4-6":    { input: 5,    output: 25,   cacheRead: 0.50, cacheWrite: 6.25 },
   "claude-opus-4-7":    { input: 5,    output: 25,   cacheRead: 0.50, cacheWrite: 6.25 },
+  "claude-opus-4-8":    { input: 5,    output: 25,   cacheRead: 0.50, cacheWrite: 6.25 },
 
   // -- Anthropic: pre-4.5 Opus (legacy, still served at original price tier) --
   "claude-opus-4-1":    { input: 15,   output: 75,   cacheRead: 1.50, cacheWrite: 18.75 },

server/pkg/agent/models.go

@@ -197,6 +197,7 @@ func cachedDiscovery(key string, fn func() ([]Model, error)) ([]Model, error) {
 func claudeStaticModels() []Model {
 	return []Model{
 		{ID: "claude-sonnet-4-6", Label: "Claude Sonnet 4.6", Provider: "anthropic", Default: true},
+		{ID: "claude-opus-4-8", Label: "Claude Opus 4.8", Provider: "anthropic"},
 		{ID: "claude-opus-4-7", Label: "Claude Opus 4.7", Provider: "anthropic"},
 		{ID: "claude-haiku-4-5-20251001", Label: "Claude Haiku 4.5", Provider: "anthropic"},
 		{ID: "claude-opus-4-6", Label: "Claude Opus 4.6", Provider: "anthropic"},

server/pkg/agent/thinking.go

@@ -102,6 +102,7 @@ var claudeEffortLabel = map[string]string{
 var claudeModelEffortAllow = map[string]map[string]bool{
 	// Opus is the only model that publicly supports xhigh; the help
 	// list still includes it for Sonnet / Haiku so we filter here.
+	"claude-opus-4-8":           {"low": true, "medium": true, "high": true, "xhigh": true, "max": true},
 	"claude-opus-4-7":           {"low": true, "medium": true, "high": true, "xhigh": true, "max": true},
 	"claude-opus-4-6":           {"low": true, "medium": true, "high": true, "xhigh": true, "max": true},
 	"claude-sonnet-4-6":         {"low": true, "medium": true, "high": true, "max": true},