feat(pricing): add runtime pricing overrides (#1204)

Add ccusage.json pricingOverrides for per-model pricing and context-limit patches.\n\nAlso fixes Pi/OpenClaw cost-mode handling so overrides apply consistently, preserves display costs where appropriate, carries overrides into statusline today totals, and updates schema/docs coverage.

Author: xiaoMaJia707

apps/ccusage/README.md

@@ -139,6 +139,7 @@ bunx ccusage monthly --compact  # Compact monthly report
 - 💰 **Cost Tracking**: Shows costs in USD for each day/month/session
 - 🔄 **Cache Token Support**: Tracks and displays cache creation and cache read tokens separately
 - 🌐 **Offline Mode**: Use pre-cached pricing data without network connectivity with `--offline`
+- 🧩 **Custom Pricing Overrides**: Override token pricing per raw model name in `ccusage.json` without rebuilding
 - 🏗️ **Claude Instance Support**: Group Claude Code usage by project with `--instances` and filter by specific projects
 - 🌍 **Timezone Support**: Configure timezone for date grouping with `--timezone` option
 - ⚙️ **Configuration Files**: Set defaults with JSON configuration files, complete with IDE autocomplete and validation