style(ui): float remaining table/card containers to design system

Repo-wide sweep for the same flat 1px-border "fake card" pattern
already fixed in Dashboard/Kanban/JobDetailsDialog/auth pages this
session -- AddJobModal, Attachments, CompaniesTable, Correspondence,
EditJobDialog, and the admin audit/system/users pages all had a table
container or content box using border+divider instead of the
floating-shadow treatment used everywhere else now.

Left AppShell.tsx/App.tsx alone -- their border:1px+divider instances
are icon-button and badge outlines, not card containers; that's a
different, correct use of the pattern.

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

@@ -374,7 +374,7 @@ export default function AddJobModal({ open, onClose, onCreated, initialUrl }: Pr
     label: string,
     helperText: string,
   ) => (
-    <Box sx={{ p: 1.5, borderRadius: 2, border: "1px solid", borderColor: "divider", backgroundColor: "background.paper" }}>
+    <Box sx={{ p: 1.5, borderRadius: 2, border: "none", boxShadow: "0px 1px 2px 0px rgba(15,23,42,0.04), 0px 8px 24px -12px rgba(15,23,42,0.12)", backgroundColor: "background.paper" }}>
       <Box sx={{ display: "flex", alignItems: "center", justifyContent: "space-between", gap: 1, flexWrap: "wrap" }}>
         <Box>
           <Typography sx={{ fontWeight: 800 }}>{label}</Typography>

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

@@ -267,7 +267,7 @@ export default function Attachments({ jobId }: { jobId: number }) {
         {uploading ? <LinearProgress sx={{ mt: 1.5, borderRadius: 999 }} /> : null}
       </Box>
 
-      <TableContainer sx={{ borderRadius: 3, border: "1px solid", borderColor: "divider" }}>
+      <TableContainer sx={{ borderRadius: 3, border: "none", boxShadow: "0px 1px 2px 0px rgba(15,23,42,0.04), 0px 8px 24px -12px rgba(15,23,42,0.12)" }}>
         <Table size="small">
           <TableHead>
             <TableRow>

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

@@ -157,7 +157,7 @@ export default function CompaniesTable() {
             ) : null}
           </Stack>
         ) : (
-          <TableContainer sx={{ borderRadius: 3, border: "1px solid", borderColor: "divider" }}>
+          <TableContainer sx={{ borderRadius: 3, border: "none", boxShadow: "0px 1px 2px 0px rgba(15,23,42,0.04), 0px 8px 24px -12px rgba(15,23,42,0.12)" }}>
             <Table>
               <TableHead>
                 <TableRow>

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

@@ -481,7 +481,7 @@ export default function Correspondence({ jobId, job }: { jobId: number; job: Job
         )}
       </Paper>
 
-      <Box sx={{ mt: 1.5, p: 1.5, borderRadius: 3, border: "1px solid", borderColor: "divider", backgroundColor: "background.default" }}>
+      <Box sx={{ mt: 1.5, p: 1.5, borderRadius: 3, border: "none", boxShadow: "0px 1px 2px 0px rgba(15,23,42,0.04), 0px 8px 24px -12px rgba(15,23,42,0.12)", backgroundColor: "background.default" }}>
         <Typography variant="overline">Linked Gmail thread continuity</Typography>
         <Typography variant="body2" sx={{ color: "text.secondary", mb: 1.25 }}>
           Linked Gmail refresh only checks threads that are already tied to this job, so new correspondence can appear here without re-importing the whole thread.

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

@@ -182,7 +182,7 @@ export default function EditJobDialog({ open, jobId, onClose, onSaved }: Props)
     <Dialog open={open} onClose={onClose} fullWidth maxWidth="md">
       <DialogTitle>{t("editJobTitle")}</DialogTitle>
       <DialogContent>
-        <Box sx={{ mt: 1, mb: 2, p: 1.5, borderRadius: 3, border: "1px solid", borderColor: "divider", backgroundColor: "background.paper" }}>
+        <Box sx={{ mt: 1, mb: 2, p: 1.5, borderRadius: 3, border: "none", boxShadow: "0px 1px 2px 0px rgba(15,23,42,0.04), 0px 8px 24px -12px rgba(15,23,42,0.12)", backgroundColor: "background.paper" }}>
           <Typography variant="body2" sx={{ color: "text.secondary" }}>
             {t("editJobIntro")}
           </Typography>