chore: sync model data with GitHub Copilot documentation

This commit automatically updates src/tokenEstimators.json and
src/modelPricing.json with new models found in the official
GitHub Copilot documentation.

Source: https://docs.github.com/en/copilot/reference/ai-models/supported-models

Author: rajbos

src/modelPricing.json

@@ -2,7 +2,7 @@
   "$schema": "http://json-schema.org/draft-07/schema#",
   "description": "Model pricing data - costs per million tokens for input and output",
   "metadata": {
-    "lastUpdated": "2026-03-02",
+    "lastUpdated": "2026-03-09",
     "sources": [
       {
         "name": "OpenAI API Pricing",
@@ -115,6 +115,13 @@
       "tier": "premium",
       "multiplier": 1
     },
+    "gpt-5.4": {
+      "inputCostPerMillion": 0.00,
+      "outputCostPerMillion": 0.00,
+      "category": "GPT-5 models",
+      "tier": "premium",
+      "multiplier": 1
+    },
     "gpt-4": {
       "inputCostPerMillion": 3.0,
       "outputCostPerMillion": 12.0,

src/tokenEstimators.json

@@ -20,6 +20,7 @@
     "gpt-5.2-codex": 0.25,
     "gpt-5.2-pro": 0.25,
     "gpt-5.3-codex": 0.25,
+    "gpt-5.4": 0.25,
     "gpt-4.1-nano": 0.25,
     "gemini-2.0-flash": 0.25,
     "gemini-2.0-flash-lite": 0.25,