Add pburl and pblastreport companion tools to the RPM

node-lookup output is useful for pivoting to Puppetboard, but there was no
quick way to turn a list of hosts into Puppetboard node-page URLs or to see
when each host last ran Puppet. These two tools close that gap and ship in the
same RPM so they are available wherever node-lookup is.

- Add pburl: reads hostnames from args or piped node-lookup output and prints
  "<host> <puppetboard-node-page-url>".
- Add pblastreport: prints "<host>\t<last-report-time>\t<url>" using
  report_timestamp from the PuppetDB v4 nodes endpoint. Supports --relative/-r
  (relative age) and --timezone/-z <IANA> (default: local timezone).
- Add internal/puppet package shared by both tools: config load, PuppetDB
  nodes query, Puppetboard URL construction, and no-TTY-safe stdin host reading.
- Add puppetboard_url config key (env NODE_LOOKUP_PUPPETBOARD_URL) to the
  shared config so config init/show scaffold it for the whole tool family.
- Build all three binaries individually (each is its own main package) and
  generate per-binary bash/zsh/fish completions in the Makefile, build-rpm.sh,
  and nfpm spec; cross-compile and attach all three per os/arch in the release
  pipeline.
- Document the tools, config key, and env var in AGENTS.md.

internal/puppet/stdin.go

@@ -0,0 +1,66 @@
+package puppet
+
+import (
+	"bufio"
+	"os"
+	"strings"
+)
+
+// StdinReader returns a buffered reader over f and true only when f actually
+// carries piped/redirected data. Terminals and character devices such as
+// /dev/null return false, and an empty pipe or empty file (immediate EOF on
+// peek) also returns false. This mirrors node-lookup's no-TTY behaviour: when
+// invoked without a real pipe the caller can fall back to arguments instead of
+// blocking on or silently consuming empty input.
+func StdinReader(f *os.File) (*bufio.Reader, bool) {
+	fi, err := f.Stat()
+	if err != nil {
+		return nil, false
+	}
+	if (fi.Mode() & os.ModeCharDevice) != 0 {
+		return nil, false // terminal or /dev/null
+	}
+	r := bufio.NewReader(f)
+	if _, err := r.Peek(1); err != nil {
+		return nil, false // empty pipe / empty file (EOF)
+	}
+	return r, true
+}
+
+// ReadHosts resolves the list of hostnames to act on. Explicit args win; failing
+// that it reads the first whitespace-separated field of each non-empty line from
+// stdin (so `node-lookup -R | pburl` and `node-lookup -1 | pburl` both work).
+// Order is preserved and duplicates are removed. Returns nil when neither args
+// nor piped stdin data are present.
+func ReadHosts(stdin *os.File, args []string) []string {
+	if len(args) > 0 {
+		return dedupe(args)
+	}
+	r, ok := StdinReader(stdin)
+	if !ok {
+		return nil
+	}
+	var hosts []string
+	sc := bufio.NewScanner(r)
+	for sc.Scan() {
+		fields := strings.Fields(sc.Text())
+		if len(fields) == 0 {
+			continue
+		}
+		hosts = append(hosts, fields[0])
+	}
+	return dedupe(hosts)
+}
+
+func dedupe(in []string) []string {
+	seen := make(map[string]struct{}, len(in))
+	out := make([]string, 0, len(in))
+	for _, s := range in {
+		if _, ok := seen[s]; ok {
+			continue
+		}
+		seen[s] = struct{}{}
+		out = append(out, s)
+	}
+	return out
+}