Spec #136: finished becomes a Series fact, Lane gate rewritten on it (#157)

finished_at lands on series (0016 seeds it from the pre-flip finished
bookmarks, then flips those bookmarks to archived), the poll gate and
eligible count read the flag instead of a per-Reader vote, PUT rejects
the finished status like any unknown value, and the web UI drops the
Finished tab, badge and finish button. Novel merge rank is archived >
reading. Per-Reader disagreement (one Reader keeps a finished Series in
reading forever) is what the flag repairs; the cutover keeps polling
state unchanged for every Series.

backend/internal/web/static/style.css

@@ -54,7 +54,7 @@
 
   --ink: #100f0e;          /* page */
   --ash: #161413;          /* recessed panel (chapter form) */
-  --dim: #0d0c0b;          /* archived / finished rows sink */
+  --dim: #0d0c0b;          /* archived rows sink */
   --rule: #221f1d;         /* hairline between sheets */
   --rule-soft: #1a1817;    /* measure edges */
   --field-line: #2c2926;
@@ -84,7 +84,6 @@
   /* One accent per action, so a press says which lane it belongs to. All three
    are held at the same weight as --brass: muted, no ember competition. */
   --slate: #7fa0c0;        /* archive */
-  --moss: #7fae86;         /* finished */
   --clay: #b5906f;         /* set chapter */
   --trash: #977671;        /* remove, resting — icons need 3:1, not 4.5:1 */
   /* A Lane needing attention: the admin page's only accent. Verdigris — cool,
@@ -148,7 +147,6 @@
     --danger-soft: #7c2c22;
     --brass: #8a681c;
     --slate: #3f6689;
-    --moss: #3d6c46;
     --clay: #7c5533;
     --trash: #8c6558;
     --patina: #1f6f66;
@@ -612,13 +610,13 @@ button { cursor: pointer; }
 .actions > *:last-child { border-right: none; }
 .actions svg { width: 17px; height: 17px; }
 .actions > *:hover { color: var(--paper); }
-/* Per-action accent on hover and press: gold favourite, slate archive, moss
-   finished, clay chapter. Remove keeps --danger, play keeps paper/ember. */
+/* Per-action accent on hover and press: gold favourite, slate archive, clay
+   chapter. Remove keeps --danger, play keeps paper/ember. */
 .actions .fav:hover, .actions .fav:active, .actions .fav:focus-visible { color: var(--brass); }
 .actions .pencil:hover, .actions .pencil:active, .actions .pencil:focus-visible { color: var(--clay); }
 .actions .box:hover, .actions .box:active, .actions .box:focus-visible { color: var(--slate); }
-.actions .finish:hover, .actions .finish:active, .actions .finish:focus-visible { color: var(--moss); }
 .actions .play { color: var(--paper); }
+
 .is-new .actions .play { color: var(--ember); }
 .actions .play:hover { background: var(--hover); }
 .actions .on { color: var(--brass); }
@@ -632,8 +630,8 @@ button { cursor: pointer; }
 .actions .remove.open { background: var(--danger-wash); color: var(--danger); }
 .is-dim .actions > * { color: var(--mute-2); }
 
-/* Three clusters by consequence: navigate (play) | organize (favourite,
-   chapter) | lifecycle (archive/restore, finish, remove). The lifecycle cells
+/* Two clusters by consequence: navigate (play) | organize (favourite,
+   chapter) | lifecycle (archive/restore, remove). The lifecycle cells
    sit on a recessed ground so the thumb reads "this one moves the series"
    before it reads which icon it landed on. */
 .actions > .lifecycle { background: var(--ash); }
@@ -712,7 +710,7 @@ button { cursor: pointer; }
   color: var(--danger-ink);
   font-weight: 600;
 }
-/* Archive and finish are reversible, so their confirm asks in grey — only the
+/* Archive is reversible, so its confirm asks in grey — only the
    irreversible remove gets the danger wash. */
 .confirm-row.calm { background: var(--ash); }
 .confirm-row.calm span { color: var(--paper-dim); }
@@ -917,9 +915,7 @@ button { cursor: pointer; }
   /* The cell border follows the icon on hover, so the accent reads as a state
      rather than a stray colour. */
   .actions .fav:hover, .actions .pencil:hover,
-  .actions .box:hover, .actions .finish:hover { border-color: currentColor; }
-
-  /* Panels line up with the body text, i.e. past the cover and its gap. */
+  .actions .box:hover { border-color: currentColor; }
   .chapter-form, .confirm-row, .error-inline {
     margin-left: calc(var(--cover-w) + var(--row-gap));
   }