feat(phase-2): separate /profile (identity) from /career (master profile)

Phase 2 — Career/Profile separation. The master career profile is the source of
truth; identity and career data are now saved independently so neither wipes the
other. CV Builder deliberately not built yet.

Backend — PUT /auth/profile is now a partial update:
- null/omitted field -> unchanged; "" -> cleared; value -> set (trimmed).
- Email/UserName never cleared to empty (login identifiers).
This lets /profile save identity fields and /career save the master-profile
fields through the same endpoint without one nulling the other. 4 new tests
cover the data-integrity guarantees (identity save keeps the CV, career save
keeps identity, empty clears, null leaves).

Frontend:
- ProfilePage save payload is now scoped by careerOnly: /career sends only
  { profileCvText, profileCvStructureJson }, /profile sends only identity.
- CareerWorkspacePage: removed the inert "CV Builder" tab (careerView) — Phase 2
  establishes the master profile only; the builder is Phase 4.
- Dropped the dead careerView prop.
- Updated the CV-save test to render career mode and assert identity is excluded.

Source-of-truth flip (CareerProfileService authoritative) stays deferred to F5
per the branch design; CareerProfileService keeps mirroring via its dual-write.

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

job-tracker-ui/src/views/CareerWorkspacePage.tsx

@@ -1,13 +1,13 @@
-import React, { useState } from "react";
+import React from "react";
 
-import { Alert, Box, Paper, Tab, Tabs, Typography } from "@mui/material";
+import { Alert, Box, Paper, Typography } from "@mui/material";
 
 import ProfilePage from "./ProfilePage";
 
+// Phase 2: /career is the Career Workspace — the master career profile, which is the single source
+// of truth for all generated documents. The CV Builder is deliberately NOT here yet (Phase 4);
+// Phase 2 only establishes the master profile. The previously-inert "CV Builder" tab was removed.
 export default function CareerWorkspacePage() {
-  const [tab, setTab] = useState<"master" | "builder">("master");
-  const [hasMasterCv, setHasMasterCv] = useState(false);
-
   return (
     <Box sx={{ display: "grid", gap: 2 }}>
       <Paper sx={{ p: 2.5, borderRadius: 4, boxShadow: "0px 8px 24px -12px rgba(15,23,42,0.12)" }}>
@@ -19,17 +19,8 @@ export default function CareerWorkspacePage() {
       <Alert severity="info" sx={{ borderRadius: 3 }}>
         Your master profile is the source of truth. Job-specific CV drafts remain separate and never overwrite it.
       </Alert>
-      <Paper sx={{ borderRadius: 4, overflow: "hidden", boxShadow: "0px 8px 24px -12px rgba(15,23,42,0.12)" }}>
-        <Tabs value={tab} onChange={(_, value) => setTab(value)} variant="scrollable" allowScrollButtonsMobile sx={{ px: 1.5, pt: 1 }}>
-          <Tab value="master" label="Master CV" />
-          <Tab value="builder" label="CV Builder" disabled={!hasMasterCv} />
-        </Tabs>
-        {!hasMasterCv ? <Alert severity="info" sx={{ mx: 2.5, mb: 0, borderRadius: 3 }}>
-          Create your Master CV first. Upload an existing CV or add your career history manually; the builder will unlock when the profile has content.
-        </Alert> : null}
-        <Box sx={{ p: { xs: 1.5, md: 2.5 } }}>
-          <ProfilePage careerOnly careerView={tab} onMasterCvAvailabilityChange={setHasMasterCv} />
-        </Box>
+      <Paper sx={{ borderRadius: 4, p: { xs: 1.5, md: 2.5 }, boxShadow: "0px 8px 24px -12px rgba(15,23,42,0.12)" }}>
+        <ProfilePage careerOnly />
       </Paper>
     </Box>
   );