feat(diagnostics): the issue composer — draft, review, screenshots, zip export (E16 S3)

After Stop (or at the cap, or from Settings → Diagnosztika's past sessions)
one dialog drafts the issue: title, description, the steps drafted from the
session's markers and page changes (a marker without a label is named by its
time), the environment (version, browser, system, window, language). Beside
it, what goes with it: the browser and server logs — each reviewable line by
line, an unticked line is not sent — and the screenshots, removable, with
paste / drop / pick to add more.

- it saves as it goes (debug_sessions.draft, migration 0090): the rendered
  markdown in the user's language, the excluded rows, and its own fields to
  reopen as it was; a sent session is read-only
- the zip export (issue.md, client.log, server.log, screenshots) is built
  from the saved draft by app/issues/bundle.py — the one definition the Gitea
  delivery (S4) will share; .log, not .jsonl, which Gitea refuses
- the log line's level tags and clock move to components/logLineParts so the
  review list draws a level the way both log viewers do

frontend/src/components/LogLine.tsx

@@ -2,28 +2,13 @@ import type { ReactNode } from "react";
 
 import type { Level } from "../lib/log";
 import { navItemAttrs } from "../lib/listNav";
+import { LEVEL_TAG, logClock } from "./logLineParts";
 
 // One log line as both log viewers draw it — "Saját napló" (this tab's ring) and the admin
 // diagnostics console (the server's stored log): time, level, event code, message, and the line opens
 // in place to whatever detail its screen has. One component, so a level reads the same on both.
 // Inside a NavGrid the keyboard walks the lines (`j`/`k`) and Enter opens one, as a click does.
 
-const LEVEL_TAG: Record<Level, { text: string; className: string }> = {
-  TRACE: { text: "TRACE", className: "text-muted opacity-80" },
-  DEBUG: { text: "DEBUG", className: "text-muted" },
-  INFO: { text: "INFO", className: "text-info" },
-  WARNING: { text: "WARN", className: "text-warn" },
-  ERROR: { text: "ERROR", className: "text-danger" },
-  CRITICAL: { text: "FATAL", className: "text-danger" },
-};
-
-/** `HH:MM:SS.mmm` in local time — a log is read to the millisecond. */
-function logClock(ts: string): string {
-  const d = new Date(ts);
-  const pad = (n: number, w = 2) => String(n).padStart(w, "0");
-  return `${pad(d.getHours())}:${pad(d.getMinutes())}:${pad(d.getSeconds())}.${pad(d.getMilliseconds(), 3)}`;
-}
-
 export default function LogLine({
   ts,
   level,