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/lib/queryKeys.ts

@@ -95,6 +95,11 @@ export const qk = {
   adminLogs: (filters: object) => ["admin-logs", filters] as const,
   adminLogFacets: (filters: object) => ["admin-log-facets", filters] as const,
   adminStorage: () => ["admin-storage"] as const,
+  // --- debug sessions (E16) ---
+  debugSessions: () => ["debug-sessions"] as const,
+  debugSession: (id: string) => ["debug-sessions", id] as const,
+  debugSessionEvents: (id: string) => ["debug-sessions", id, "events"] as const,
+  debugScreenshots: (id: string) => ["debug-sessions", id, "screenshots"] as const,
   adminDownloads: () => ["admin-downloads"] as const,
   adminQuota: (days: number) => ["admin-quota", days] as const,
   demoWhitelist: () => ["demo-whitelist"] as const,