p3: search API, pinned sources, cache, CLI

POST /v1/search and /v2/search fan in SearXNG, Brave LLM Context, and
Tavily from config-fixed endpoints. Public sources refuse private A
records; SearXNG is a loopback-only client, not the fetch guard.

Cache keys include caller class. Restricted callers search like the
fleet; logs omit query, hosts, URLs, and upstream errors. Degraded
results are not stored. Tavily sends search_depth=basic and drops
answer. Missing keys surface in /healthz.

Default-on sources stay off until the bake-off. Query harvest is not
in this commit.

cmd/sift/searchcmd.go

@@ -0,0 +1,86 @@
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"flag"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+)
+
+func searchMain() {
+	fs := flag.NewFlagSet("search", flag.ContinueOnError)
+	fs.SetOutput(io.Discard)
+	k := fs.Int("k", 0, "result cap")
+	asJSON := fs.Bool("json", false, "native envelope")
+	args := os.Args[1:]
+	flagArgs, pos, err := splitAroundPositional(args, map[string]bool{"k": true})
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(2)
+	}
+	if err := fs.Parse(flagArgs); err != nil {
+		fmt.Fprintln(os.Stderr, searchUsage)
+		os.Exit(2)
+	}
+	if len(pos) != 1 {
+		fmt.Fprintln(os.Stderr, searchUsage)
+		os.Exit(2)
+	}
+	query := pos[0]
+	base, key, err := loadClient()
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(5)
+	}
+	body := map[string]any{"query": query}
+	if *k > 0 {
+		body["k"] = *k
+	}
+	raw, _ := json.Marshal(body)
+	req, err := http.NewRequest(http.MethodPost, base+"/v1/search", bytes.NewReader(raw))
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(5)
+	}
+	req.Header.Set("Authorization", "Bearer "+key)
+	req.Header.Set("Content-Type", "application/json")
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(5)
+	}
+	defer resp.Body.Close()
+	var env map[string]any
+	if err := json.NewDecoder(resp.Body).Decode(&env); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(5)
+	}
+	if resp.StatusCode != 200 {
+		msg, _ := env["error"].(string)
+		fmt.Fprintln(os.Stderr, msg)
+		os.Exit(exitFor(resp.StatusCode, msg))
+	}
+	if *asJSON {
+		enc := json.NewEncoder(os.Stdout)
+		enc.SetIndent("", "  ")
+		_ = enc.Encode(env)
+		return
+	}
+	results, _ := env["results"].([]any)
+	for i, it := range results {
+		m, _ := it.(map[string]any)
+		if i > 0 {
+			fmt.Println()
+		}
+		fmt.Println(m["title"])
+		fmt.Println(m["url"])
+		if sn, _ := m["snippet"].(string); sn != "" {
+			fmt.Println(sn)
+		}
+	}
+}
+
+const searchUsage = `usage: sift search "<query>" [--k N] [--json]`