feat(ai): AI Workspace panel on every job application

Phase 5 frontend. A new "AI Workspace" tab in the job details dialog hosts the
five suggestion modules (Job Analysis, Career Match, Cover Letter with tone,
Interview Prep, Application Review) with a generate flow, a dependency-free
markdown renderer for results, and a history sidebar (reuse / compare / copy /
delete). Everything is suggestion-only — copy to keep; nothing auto-applies.

- aiWorkspace.ts (types + API), components/AiWorkspacePanel.tsx,
  components/Markdown.tsx (no HTML injection surface — renders React nodes)
- mounted as the last tab in JobDetailsDialog (index-safe, no reindexing)
- 3 tests (generate flow, cover-letter mode, markdown); tsc + build clean

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

job-tracker-ui/src/components/JobDetailsDialog.tsx

@@ -28,6 +28,7 @@ import { emptyTailoredCvDraft, joinLines, normalizeTailoredCvDraft, splitLines }
 
 import Correspondence from "./Correspondence";
 import Attachments from "./Attachments";
+import AiWorkspacePanel from "./AiWorkspacePanel";
 import JobFlowBar from "./JobFlowBar";
 import GradientButton from "./GradientButton";
 import { useI18n } from "../i18n/I18nProvider";
@@ -697,6 +698,7 @@ export default function JobDetailsDialog({ open, jobId, onClose, initialTab = 0,
           <Tab label={t("jobDetailsTabInterviewPrep")} />
           <Tab label={t("jobTableReadiness")} />
           {isAdmin ? <Tab label={t("jobDetailsTabHistory")} /> : null}
+          <Tab label="AI Workspace" />
         </Tabs>
 
         {attachmentPicker}
@@ -1270,6 +1272,8 @@ export default function JobDetailsDialog({ open, jobId, onClose, initialTab = 0,
             {history.length === 0 ? <Typography sx={{ color: "text.secondary" }}>{t("jobDetailsNoHistory")}</Typography> : history.map((entry) => <PaperRow key={entry.id} type={entry.type} oldValue={entry.oldValue} newValue={entry.newValue} at={entry.at} note={entry.note} />)}
           </Box>
         )}
+        {/* AI Workspace is the last tab: index depends on whether the admin History tab is present. */}
+        {tab === (isAdmin ? 10 : 9) && jobId && <AiWorkspacePanel jobId={jobId} />}
       </DialogContent>
     </Dialog>
   );