feat: documentation pages and updated model pricing

- Add 13 documentation pages under /docs (getting-started, concepts, SDK refs, integrations, API reference, self-hosting, OpenCode plugin)
- Shared docs layout with collapsible sidebar navigation
- Update model pricing across all SDKs: add GPT-5.x, GPT-4.1, o3/o4-mini, Claude 4.5 series, claude-opus-4-6
- Update trace-analytics context window lookup with current models

apps/web/src/components/trace-analytics.tsx

@@ -467,12 +467,27 @@ function TokenUsageGauge({ trace }: { trace: Trace }) {
       null;
 
     const modelContextWindows: Record<string, number> = {
+      "gpt-5.2": 128000,
+      "gpt-5.1": 128000,
+      "gpt-5": 128000,
+      "gpt-5-mini": 128000,
+      "gpt-5-nano": 128000,
+      "gpt-4.1": 1047576,
+      "gpt-4.1-mini": 1047576,
+      "gpt-4.1-nano": 1047576,
+      "o3": 200000,
+      "o3-mini": 200000,
+      "o4-mini": 200000,
       "gpt-4": 8192,
       "gpt-4-32k": 32768,
       "gpt-4-turbo": 128000,
       "gpt-4o": 128000,
       "gpt-4o-mini": 128000,
       "gpt-3.5-turbo": 16385,
+      "claude-opus-4-6": 200000,
+      "claude-4.5-opus": 200000,
+      "claude-4.5-sonnet": 200000,
+      "claude-4.5-haiku": 200000,
       "claude-3-opus": 200000,
       "claude-3-sonnet": 200000,
       "claude-3-haiku": 200000,