tabs: render schedules as a single table with tilted agent columns (closes #535)

Replaces the per-schedule card layout with one table:

  | # | src | next | every | owner | body | …agents… | actions |
  |---|-----|------|-------|-------|------|----------|---------|
  | 5 | op  | 5m   | 10m   | mara  | "…"  | ✓ ✓ . ✓ |  ↯ ✎ ✕  |

Each schedule is one <tr> in the tbody. Agent columns are dynamic —
operator + manager + live containers + any "extra" name that appears
as a target on some schedule but isn't a current container (same
membership rule buildTargetChips uses, so the table + new/edit forms
agree on what's addressable). Per-agent cells:

  - active target  → <button>✓</button> that cancels just that target
    on click (replaces the per-row ✕ from the old targets sub-table)
  - cancelled target → muted ✕ glyph (no button; re-add flows through
    the edit form's targets multi-select)
  - not a target → empty cell

Agent column headers tilt -45° via CSS so each column reads as 28px
of horizontal real estate instead of the full word width. Standard
rotated-header pattern: 95px-tall <th> with position:relative, inner
<div> positioned absolute at bottom-left, transform rotates about
left-bottom.

Body cell truncates with ellipsis + full-text title. Description used
to be a separate visible block on the card layout; the table folds
it into the body cell's title to keep row height tight. If mara wants
description visible in-table it's a small follow-up — easier to
iterate on a rejection.

Edit form expands inline into a colspan'd row underneath the schedule
row it edits (instead of inside the card). Wrapper drops the form's
background so it reads as a row extension.

No backend changes; everything renders from existing schedulesState
+ containersState.

frontend/packages/dashboard/src/dashboard.css

@@ -1759,60 +1759,112 @@ body.flow-shell .tabbar .tab.active.tab-link {
 }
 .schedule-interval-preview-oneshot { color: var(--muted); font-style: italic; }
 
-.schedules {
-  display: flex;
-  flex-direction: column;
-  gap: 0.5em;
-}
-.schedule-row {
-  padding: 0.6em 0.9em;
-  background: rgba(24, 24, 37, 0.55);
-  border: 1px solid var(--border);
-  border-radius: 4px;
-  display: flex;
-  flex-direction: column;
-  gap: 0.4em;
-}
-.schedule-row.schedule-cancelled { opacity: 0.55; }
-.schedule-head {
-  display: flex;
-  flex-wrap: wrap;
-  align-items: center;
-  gap: 0.4em;
-}
-.schedule-description {
-  color: var(--muted);
-  font-style: italic;
-  font-size: 0.95em;
-}
-.schedule-body {
-  white-space: pre-wrap;
-  word-break: break-word;
-  background: var(--bg);
-  border: 1px solid var(--border);
-  border-radius: 3px;
-  padding: 0.5em 0.7em;
-}
-.schedule-targets-table {
+/* #535 — schedules-as-table. One row per schedule, attribute columns
+   on the left, one ✓/✕ column per agent in the middle, actions
+   column on the right. Agent column headers tilt -45° so a stack of
+   short agent names fits in ~28px each. */
+.schedules-table {
   width: 100%;
   border-collapse: collapse;
   font-size: 0.9em;
 }
-.schedule-targets-table th,
-.schedule-targets-table td {
-  padding: 0.25em 0.6em;
+.schedules-table thead th {
+  vertical-align: bottom;
+  padding: 0.3em 0.5em;
   text-align: left;
-  border-bottom: 1px solid var(--border);
-}
-.schedule-targets-table th {
   color: var(--muted);
   font-weight: normal;
   text-transform: uppercase;
   letter-spacing: 0.05em;
   font-size: 0.8em;
+  border-bottom: 1px solid var(--border);
+}
+.schedules-table-id { width: 3em; }
+.schedules-table-body-th { min-width: 12em; }
+.schedules-table-actions-th { width: 7em; }
+/* Tilted agent column headers (#535). Header cell is narrow (~28px)
+   and tall (~90px); the inner <div> rotates -45° about its bottom-left
+   corner, with a translate to slide the text up alongside the cell
+   border. The inner <span> carries the actual baseline so the
+   underline (border-bottom on the cell) aligns with the rotated text. */
+.schedules-table-agent-th {
+  width: 28px;
+  min-width: 28px;
+  height: 95px;
+  padding: 0 !important;
+  vertical-align: bottom;
+  white-space: nowrap;
+  text-transform: none !important;
+  letter-spacing: 0 !important;
+  position: relative;
+}
+.schedules-table-agent-th > div {
+  position: absolute;
+  bottom: 4px;
+  left: 14px;
+  transform-origin: left bottom;
+  transform: rotate(-45deg);
+  font-family: ui-monospace, 'JetBrains Mono', monospace;
+  font-size: 0.9em;
+  color: var(--fg);
+}
+.schedules-table-agent-th > div > span {
+  display: inline-block;
+  padding: 0 4px 1px;
+}
+.schedules-table tbody td {
+  padding: 0.3em 0.5em;
+  border-top: 1px solid var(--border);
+  vertical-align: middle;
+}
+.schedules-table-row-cancelled td { opacity: 0.55; }
+.schedules-table-body-cell {
+  max-width: 30em;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+  font-family: ui-monospace, 'JetBrains Mono', monospace;
+  font-size: 0.9em;
+}
+.schedules-table-check {
+  width: 28px;
+  text-align: center;
+  padding: 0.3em 0 !important;
+}
+.schedules-table-check-btn {
+  background: transparent;
+  border: 0;
+  color: var(--green);
+  cursor: pointer;
+  padding: 0.1em 0.3em;
+  font-family: inherit;
+  font-size: 1em;
+}
+.schedules-table-check-btn:hover:not(:disabled) {
+  color: var(--red);
+}
+.schedules-table-check-btn:disabled {
+  cursor: default;
+}
+.schedules-table-check-cancelled {
+  color: var(--muted);
+  font-size: 0.9em;
+}
+.schedules-table-actions {
+  text-align: right;
+  white-space: nowrap;
+}
+.schedules-table-actions .btn-inline-small {
+  margin-left: 0.3em;
+}
+/* Edit form expands inline into a colspan'd row underneath the
+   schedule it edits. Wrapper drops the form's normal background so it
+   reads as "an extension of the row above" instead of a free-floating
+   card. */
+.schedules-table-edit-row > td {
+  padding: 0.5em 0.8em 0.8em !important;
+  background: rgba(24, 24, 37, 0.4);
 }
-.schedule-targets-table tr:last-child td { border-bottom: 0; }
-.schedule-target-cancelled td { opacity: 0.5; }
 .btn-inline-small {
   font-size: 0.7em;
   padding: 0.1em 0.45em;