Update Anthropic model: claude-sonnet-4-20250514 → claude-sonnet-4-6

Old dated model ID returns 404 from Anthropic API. Switch to current
short alias (Sonnet 4.6) in both Python library default and JS browser
pipeline, plus pricing table.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: BirdInTheTree

src/tvplot/html/parts/pipeline.js

@@ -68,7 +68,7 @@ async function callAnthropic(systemPrompt, userMessage, apiKey, onChunk, maxToke
       'content-type': 'application/json',
     },
     body: JSON.stringify({
-      model: 'claude-sonnet-4-20250514',
+      model: 'claude-sonnet-4-6',
       max_tokens: maxTokens || _DEFAULT_MAX_TOKENS_ANTHROPIC,
       stream: true,
       system: systemPrompt,

src/tvplot/llm.py

@@ -30,7 +30,7 @@
 
 # Pricing per million tokens (USD) — updated as of 2026-03
 _PRICING = {
-    "claude-sonnet-4-20250514": {"input": 3.0, "output": 15.0},
+    "claude-sonnet-4-6": {"input": 3.0, "output": 15.0},
     "claude-haiku-4-5-20251001": {"input": 0.80, "output": 4.0},
     "gpt-4o": {"input": 2.50, "output": 10.0},
 }
@@ -112,7 +112,7 @@ def resolved_model(self) -> str:
         if self.model:
             return self.model
         defaults = {
-            "anthropic": "claude-sonnet-4-20250514",
+            "anthropic": "claude-sonnet-4-6",
             "openai": "gpt-4o",
         }
         # Check known providers