feat(audit): add pricing signature guards and reporting

Add snapshot, signature, and drift guard support for Vertex AI, Cloudflare Workers AI, and Perplexity API, backed by a queryable audit table and recent-window view.

This commit also wires the audit query layer into daily signal materialization and report generation so structure drift becomes a first-class signal instead of a log-only artifact.

scripts/import_perplexity_pricing_test.go

@@ -0,0 +1,80 @@
+//go:build llm_script
+
+package main
+
+import (
+	"bytes"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestParsePerplexityPricingCatalogBuildsRecords(t *testing.T) {
+	raw, err := os.ReadFile(filepath.Join("testdata", "perplexity_pricing_sample.md"))
+	if err != nil {
+		t.Fatalf("读取 fixture 失败: %v", err)
+	}
+
+	records, err := parsePerplexityPricingCatalog(string(raw))
+	if err != nil {
+		t.Fatalf("parsePerplexityPricingCatalog 返回错误: %v", err)
+	}
+	if len(records) != 5 {
+		t.Fatalf("期望 5 条 Perplexity 价格记录，实际 %d", len(records))
+	}
+	if records[0].ModelID != "perplexity-perplexity-sonar" {
+		t.Fatalf("首条 modelID 错误: %q", records[0].ModelID)
+	}
+	if records[1].ProviderName != "Anthropic" {
+		t.Fatalf("Anthropic provider 归一化错误: %q", records[1].ProviderName)
+	}
+	if records[3].ModelSourceURL != "https://ai.google.dev/gemini-api/docs/models#gemini-3.1-pro-preview" {
+		t.Fatalf("Gemini 模型文档链接错误: %q", records[3].ModelSourceURL)
+	}
+}
+
+func TestRunPerplexityPricingImportDryRunPrintsSummary(t *testing.T) {
+	var out bytes.Buffer
+	err := runPerplexityPricingImport(perplexityPricingImportConfig{
+		URL:     defaultPerplexityPricingFetchURL,
+		Fixture: filepath.Join("testdata", "perplexity_pricing_sample.md"),
+		DryRun:  true,
+	}, nil, &out)
+	if err != nil {
+		t.Fatalf("runPerplexityPricingImport 返回错误: %v", err)
+	}
+	output := out.String()
+	for _, want := range []string{
+		"source=perplexity-pricing-import",
+		"models=5",
+		"operator=Perplexity API",
+		"dry_run=true",
+	} {
+		if !strings.Contains(output, want) {
+			t.Fatalf("输出缺少 %q，实际: %q", want, output)
+		}
+	}
+}
+
+func TestParsePerplexityPricingCatalogAcceptsExtraColumnsAndDocAtTail(t *testing.T) {
+	raw := "" +
+		"\n# Models\n" +
+		"\n| Model | Family | Input Price | Output Price | Notes | Provider Documentation |\n" +
+		"| --- | --- | --- | --- | --- | --- |\n" +
+		"| `openai/gpt-5.5` | GPT-5 | \\$1.25 / 1M tokens | \\$10.00 / 1M tokens | flagship | [GPT-5.5](https://platform.openai.com/docs/models/gpt-5.5) |\n"
+
+	records, err := parsePerplexityPricingCatalog(raw)
+	if err != nil {
+		t.Fatalf("parsePerplexityPricingCatalog 返回错误: %v", err)
+	}
+	if len(records) != 1 {
+		t.Fatalf("期望 1 条 Perplexity 价格记录，实际 %d", len(records))
+	}
+	if records[0].ModelSourceURL != "https://platform.openai.com/docs/models/gpt-5.5" {
+		t.Fatalf("文档链接错误: %q", records[0].ModelSourceURL)
+	}
+	if records[0].InputPrice != 1.25 || records[0].OutputPrice != 10 {
+		t.Fatalf("价格解析错误: %v / %v", records[0].InputPrice, records[0].OutputPrice)
+	}
+}