fix(auth): Google Sign-In audience mismatch + remove per-user accent color

Root cause of "Google authentication failed": appsettings.Development.json
had Auth:GoogleClientId set to the literal placeholder
"CHANGE_ME_GOOGLE_CLIENT_ID" while the frontend's .env.development had a
real (already-public, already-committed) client ID -- every Google ID
token's audience check failed against the backend's placeholder. Fixed
by setting the same real client ID on both sides (a client ID is a
public identifier, not a secret, safe to commit -- unlike a client
secret). Also enabled Auth:AllowRegistration in dev so the existing
Google-first self-serve-signup path (auto-create on unmatched verified
email, auto-link on matching verified email -- built during Wave 7) is
actually exercisable locally.

Wired the previously-missing Auth__MicrosoftClientId /
NEXT_PUBLIC_MICROSOFT_CLIENT_ID into docker-compose.yml/.env.example
(distinct from the existing MICROSOFT_CLIENT_ID used for Outlook mail
linking) -- Microsoft sign-in was never deployable, a leftover gap from
when it was built. Fixed a stale env-var name in the Microsoft setup
hint copy (still said REACT_APP_*, predates the Next.js migration).

Removed the per-user accent color picker entirely: it was purely
client-side (localStorage + theme.ts), never touched the backend/DB.
theme.ts now hardcodes a single ACCENT constant; themePrefs.ts drops
get/set/clearAccentColor; App.tsx and SettingsView.tsx drop the
accentColor prop threading. Dead accent-related i18n keys removed from
both locales.

Consolidated Settings' "Account" tab (duplicated GoogleAuthCard, which
already lives on the Profile page) into Profile: moved AuthStatusCard
and EmailProviderConnections there alongside the existing Google/
Microsoft auth cards, so identity/account-linking lives in one place.
Settings drops from 5 tabs to 4 and its General tab uses a consistent
SectionCard layout instead of ad-hoc per-card styling.

Verified: dotnet build/test (177/177) and npm build/test (57/57) both
green; confirmed live against a running dev server that /auth/config
now reports googleEnabled with the corrected client ID, Settings has
no accent controls, and Profile shows the consolidated auth section.

job-tracker-ui/src/theme.ts

@@ -2,6 +2,10 @@ import { alpha, createTheme, darken, lighten } from "@mui/material/styles";
 
 type PaletteLike = Record<string, any>;
 
+// Single global brand accent -- matches the dark sidebar/landing page indigo used throughout
+// the app. Not user-configurable; see jobbjakt-nextjs-migration memory / UI rework notes.
+const ACCENT = "#6366F1";
+
 function buildPrimary(main: string) {
   return {
     lighter: lighten(main, 0.82),
@@ -12,7 +16,7 @@ function buildPrimary(main: string) {
   };
 }
 
-function buildLightPalette(accentColor: string): PaletteLike {
+function buildLightPalette(): PaletteLike {
   const textPrimary = "#1B1B1F";
   const textSecondary = "#46464F";
 
@@ -24,7 +28,7 @@ function buildLightPalette(accentColor: string): PaletteLike {
   const disabledBackground = "#E4E1E6";
 
   return {
-    primary: buildPrimary(accentColor || "#6366F1"),
+    primary: buildPrimary(ACCENT),
     secondary: {
       lighter: "#E0E0FF",
       light: "#C3C4E4",
@@ -82,14 +86,14 @@ function buildLightPalette(accentColor: string): PaletteLike {
     // from the product mockups; cards/inputs (paper) sit above it.
     background: { default: "#F4F6FB", paper: background },
     action: {
-      hover: alpha(accentColor || "#6366F1", 0.05),
+      hover: alpha(ACCENT, 0.05),
       disabled: alpha(disabled, 0.6),
       disabledBackground: alpha(disabledBackground, 0.9),
     },
   };
 }
 
-function buildDarkPalette(accentColor: string): PaletteLike {
+function buildDarkPalette(): PaletteLike {
   const bg = "#0B0B0E";
   const paper = "#111116";
   const divider = alpha("#FFFFFF", 0.10);
@@ -101,7 +105,7 @@ function buildDarkPalette(accentColor: string): PaletteLike {
   const disabledBackground = alpha("#FFFFFF", 0.08);
 
   return {
-    primary: buildPrimary(accentColor || "#6366F1"),
+    primary: buildPrimary(ACCENT),
     secondary: {
       lighter: alpha(secondaryMain, 0.22),
       light: alpha(secondaryMain, 0.14),
@@ -157,7 +161,7 @@ function buildDarkPalette(accentColor: string): PaletteLike {
     divider,
     background: { default: bg, paper },
     action: {
-      hover: alpha(accentColor || "#6366F1", 0.16),
+      hover: alpha(ACCENT, 0.16),
       disabled: alpha("#FFFFFF", 0.5),
       disabledBackground,
     },
@@ -196,9 +200,9 @@ function buildTypography() {
   };
 }
 
-export const getTheme = (_mode: "light" | "dark", accentColor: string) => {
-  const lightPalette = buildLightPalette(accentColor);
-  const darkPalette = buildDarkPalette(accentColor);
+export const getTheme = (_mode: "light" | "dark") => {
+  const lightPalette = buildLightPalette();
+  const darkPalette = buildDarkPalette();
 
   const theme = createTheme({
     breakpoints: {