fix(frontend): mobile layout polish + overflow handling (0.60.1)

Visual cleanup pass after wiring up real data — the placeholder
content used during the five mobile phases hid a few sharp edges
that became obvious as soon as user-supplied tags / author handles
/ descriptions hit the screen.

- Mobile gutter unified at 16px (was 12px) — matches iOS / Material
  standard and gives chips, description text, and chapter rows
  visible breathing room from the screen edge. Hero negative margin
  in /manga/[id] tracks the change so the bleed still hits viewport.
- Catalog grid switched from 2 columns to 4 with
  `repeat(4, minmax(0, 1fr))` (per user preference). The `minmax(0,
  ...)` is load-bearing — without it the implicit `minmax(auto, 1fr)`
  lets a long single-word card title push the column past the
  viewport edge. MangaCard's `.author` and `.genres` lines hide
  below 640px so every card in the 4-col layout has identical height
  (cover + 2-line title clamp).
- Same minmax(0, 1fr) trick applied to the detail page's
  `.overview` grid track, plus defensive `min-width: 0` /
  `max-width: 100%` on `.meta` and `.chip-row` so a long
  unbreakable tag or romanized URL can't drag the metadata column
  past the article gutter.
- BottomNav swapped from `grid-auto-columns` (= `minmax(auto, 1fr)`)
  to an explicit `repeat(4, minmax(0, 1fr))`, plus `min-width: 0` on
  `.tab` and an ellipsizing `.label` so a long tab label stays
  inside the bar. The Browse placeholder is replaced with Upload —
  a real action, no longer a no-op duplicate of Home.
- Hero appbar gets 16px all-around inset (was 8px) so the back / ⋯
  circle buttons aren't kissing the screen edge or the hero top.
  Hero content gets 20px horizontal padding so the cover thumb +
  title sit visibly off the hero scrim. Description gains
  `overflow-wrap: anywhere` for long URLs / romanized titles.
- Chip now allows `overflow-wrap: anywhere` on its label and uses
  `max-width: 100%` + `min-width: 0` so a long token wraps to its
  own line within the chip-row and ellipsizes inside the chip.
- Mobile catalog search-row gains `flex-basis: calc(100% - 36px -
  --space-2)` so the search input takes its own line — the Filter
  and Sort chips wrap to a second row instead of squeezing the
  input down to a few characters.
- Global safety net: `html, body { overflow-x: hidden }` below
  640px so any future bug that lets an element overflow the
  viewport doesn't expose touch-pan that shifts the whole layout.
  Fixed descendants (bottom nav, CTA bar) are unaffected.
- audit.mjs — small dev helper that walks all 12 user-facing
  routes at 390px and reports horizontal overflow, internal
  scrollers, and edge-bleeding controls. Used to drive these fixes
  and useful for future mobile changes.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/lib/components/Chip.svelte

@@ -69,7 +69,11 @@
         border: 1px solid var(--border);
         color: var(--text);
         text-decoration: none;
-        white-space: nowrap;
+        /* Cap the chip at its row width so a long author handle or
+           tag slug doesn't push past the chip-row's edge. min-width: 0
+           is the flex-item escape so it can actually shrink. */
+        max-width: 100%;
+        min-width: 0;
     }
 
     a.chip:hover {
@@ -91,8 +95,14 @@
     }
 
     .chip-label {
+        min-width: 0;
         overflow: hidden;
         text-overflow: ellipsis;
+        white-space: nowrap;
+        /* `anywhere` lets a no-space token (a romanized title, a tag
+           slug) break before it ellipsizes — keeps the chip inside
+           its row even when the label has no soft-break points. */
+        overflow-wrap: anywhere;
     }
 
     .chip-remove {