Upgrade default Claude Opus model to 4.8

Bump the default Opus route/model from claude-opus-4-7 to claude-opus-4-8
across provider presets (claude, claudeDesktop, hermes, openclaw, opencode,
universal), i18n locales (zh/en/ja/zh-TW), pricing seed data, and the
user-manual docs.

- Add claude-opus-4-8 pricing row ($5/$25/$0.50/$6.25); keep the 4-7 row
  for historical usage stats (seeded via INSERT OR IGNORE).
- Claude Desktop proxy: accept bidirectional opus 4-7 <-> 4-8 route alias
  during rollout so previously saved routes keep resolving.
- thinking_optimizer: route opus-4-8 through adaptive thinking and normalize
  dotted model ids (also fixes dotted 4-6/4-7 falling back to legacy).
- usage_stats: normalize Bedrock/Vertex/aggregator opus-4-8 ids to base
  pricing.

Also merge role:"system" messages into the Gemini systemInstruction in the
Anthropic->Gemini transform.

src/types/omo.ts

@@ -29,7 +29,7 @@ export const OMO_BUILTIN_AGENTS: OmoAgentDef[] = [
     display: "Sisyphus",
     descKey: "omo.agentDesc.sisyphus",
     tooltipKey: "omo.agentTooltip.sisyphus",
-    recommended: "claude-opus-4-7",
+    recommended: "claude-opus-4-8",
     group: "main",
   },
   {
@@ -45,7 +45,7 @@ export const OMO_BUILTIN_AGENTS: OmoAgentDef[] = [
     display: "Prometheus",
     descKey: "omo.agentDesc.prometheus",
     tooltipKey: "omo.agentTooltip.prometheus",
-    recommended: "claude-opus-4-7",
+    recommended: "claude-opus-4-8",
     group: "main",
   },
   {
@@ -162,7 +162,7 @@ export const OMO_BUILTIN_CATEGORIES: OmoCategoryDef[] = [
     display: "Unspecified High",
     descKey: "omo.categoryDesc.unspecifiedHigh",
     tooltipKey: "omo.categoryTooltip.unspecifiedHigh",
-    recommended: "claude-opus-4-7",
+    recommended: "claude-opus-4-8",
   },
   {
     key: "writing",
@@ -281,7 +281,7 @@ export const OMO_BACKGROUND_TASK_PLACEHOLDER = `{
     "google": 10
   },
   "modelConcurrency": {
-    "anthropic/claude-opus-4-7": 2,
+    "anthropic/claude-opus-4-8": 2,
     "google/gemini-3-flash": 10
   }
 }`;
@@ -320,7 +320,7 @@ export const OMO_SLIM_BUILTIN_AGENTS: OmoAgentDef[] = [
     display: "Orchestrator",
     descKey: "omo.slimAgentDesc.orchestrator",
     tooltipKey: "omo.slimAgentTooltip.orchestrator",
-    recommended: "claude-opus-4-7",
+    recommended: "claude-opus-4-8",
     group: "main",
   },
   {