Add the appliance web UI look, interface names, MCP and REST API, local zone

Web UI: dark/light themes (appliance layout, sidebar, switch checkboxes),
theme preference on the Advanced page, Changes page with the pending diff.

Interface names: router.interfaces.<name>.mac, lans.<l>.deviceName and
pppoe.vlanName; a rename is staged for the next reboot by router-apply.

Remote access: an MCP server (POST /mcp) and an OpenAPI REST API
(/api/v1, /api/openapi.json) with the same tokens, scopes, limits and audit
log; tools to read status, settings, leases, logs (get_logs), and to edit
and check the saved settings (never applied). Tokens on the API access page.

Firewall: a reserved `local` zone (the router itself) as the destination of
rules, so the web UI or SSH can be allowed from the WAN.

PLAN.md lists what is still left.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AeFqV9dZrK6nipHkPfyM4F

pkgs/router-webui/logs.go

@@ -0,0 +1,120 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+// get_logs: the system journal, read-only, through journalctl with its
+// arguments built here (no shell), so that nothing a caller sends can become
+// an option.
+
+var (
+	unitRe  = regexp.MustCompile(`^[a-zA-Z0-9][a-zA-Z0-9@:._-]{0,79}$`)
+	timeRe  = regexp.MustCompile(`^[0-9A-Za-z :.+/_,-]{1,40}$`)
+	prioRe  = regexp.MustCompile(`^([0-7]|emerg|alert|crit|err|warning|notice|info|debug)$`)
+	maxLogs = 1000
+	logSize = 256 << 10
+)
+
+// runJournal runs journalctl (replaced in tests).
+var runJournal = command
+
+type logQuery struct {
+	Unit     string `json:"unit"`
+	Lines    int    `json:"lines"`
+	Since    string `json:"since"`
+	Until    string `json:"until"`
+	Priority string `json:"priority"`
+	Grep     string `json:"grep"`
+	Boot     *int   `json:"boot"`
+}
+
+// journalArgs turns a query into journalctl's arguments.
+func journalArgs(q logQuery) ([]string, error) {
+	if q.Lines == 0 {
+		q.Lines = 100
+	}
+	if q.Lines < 1 || q.Lines > maxLogs {
+		return nil, argError(fmt.Sprintf("lines must be 1 to %d", maxLogs))
+	}
+	args := []string{"--no-pager", "-o", "short-iso", "--lines=" + strconv.Itoa(q.Lines)}
+	switch {
+	case q.Unit == "kernel":
+		args = append(args, "-k")
+	case q.Unit != "":
+		if !unitRe.MatchString(q.Unit) {
+			return nil, argError("unit: a unit name like router-webui or router-pppoe.service, or kernel")
+		}
+		args = append(args, "--unit="+q.Unit)
+	}
+	for _, t := range []struct{ flag, v string }{{"--since=", q.Since}, {"--until=", q.Until}} {
+		if t.v == "" {
+			continue
+		}
+		if !timeRe.MatchString(t.v) {
+			return nil, argError(strings.TrimPrefix(strings.TrimSuffix(t.flag, "="), "--") + ": a time like \"1 hour ago\", \"-2h\", \"yesterday\" or \"2026-10-31 10:00:00\"")
+		}
+		args = append(args, t.flag+t.v)
+	}
+	if q.Priority != "" {
+		if !prioRe.MatchString(q.Priority) {
+			return nil, argError("priority: 0-7 or emerg, alert, crit, err, warning, notice, info, debug (that level and worse)")
+		}
+		args = append(args, "--priority="+q.Priority)
+	}
+	if q.Grep != "" {
+		if len(q.Grep) > 200 {
+			return nil, argError("grep: at most 200 characters")
+		}
+		args = append(args, "--grep="+q.Grep, "--case-sensitive=false")
+	}
+	if q.Boot != nil {
+		if *q.Boot > 0 || *q.Boot < -50 {
+			return nil, argError("boot: 0 (this boot), -1 (the one before), ...")
+		}
+		args = append(args, "--boot="+strconv.Itoa(*q.Boot))
+	}
+	return args, nil
+}
+
+var logsTool = mcpTool{
+	name: "get_logs", scope: scopeRead,
+	description: "Lines of the system journal, oldest first (the last `lines` that match). Without `unit` all units. Useful units: router-pppoe (the PPPoE connection: connects and disconnects), router-webui, router-apply, systemd-networkd, kea-dhcp4-server, nftables, wireguard-*; `kernel` for the kernel log. Search a text with `grep`, narrow by `since` (\"1 hour ago\", \"2026-10-31 10:00:00\"), `priority` (err = errors and worse) or `boot` (0 this boot, -1 the previous).",
+	schema: map[string]any{
+		"type": "object",
+		"properties": map[string]any{
+			"unit":     map[string]any{"type": "string", "description": "A systemd unit (router-pppoe, router-webui.service, ...) or `kernel`."},
+			"lines":    map[string]any{"type": "integer", "minimum": 1, "maximum": maxLogs, "default": 100, "description": "How many lines at most."},
+			"since":    map[string]any{"type": "string", "description": "Only entries since then: \"1 hour ago\", \"yesterday\", \"2026-10-31 10:00:00\"."},
+			"until":    map[string]any{"type": "string", "description": "Only entries until then."},
+			"priority": map[string]any{"type": "string", "description": "This level and worse: 0-7 or emerg, alert, crit, err, warning, notice, info, debug."},
+			"grep":     map[string]any{"type": "string", "description": "Only entries matching this regular expression (case insensitive)."},
+			"boot":     map[string]any{"type": "integer", "maximum": 0, "description": "0 is the current boot, -1 the one before, ... Without it all boots the journal holds."},
+		},
+	},
+	run: func(a *app, raw json.RawMessage) (any, error) {
+		var q logQuery
+		if err := json.Unmarshal(raw, &q); err != nil {
+			return nil, argError("bad arguments: " + err.Error())
+		}
+		args, err := journalArgs(q)
+		if err != nil {
+			return nil, err
+		}
+		out, err := runJournal("journalctl", args...)
+		if err != nil && out == "" {
+			return nil, fmt.Errorf("journalctl: %w", err)
+		}
+		if len(out) > logSize {
+			out = "[…]\n" + out[len(out)-logSize:]
+		}
+		if out == "" || strings.HasPrefix(out, "-- No entries --") {
+			return "No matching entries.", nil
+		}
+		return out, nil
+	},
+}