fix(web): clearer topology/identity copy, capped description width, mobile More-nav, preset spacing

Console polish on the Virtual displays card + shell:
- Topology help now leads with the streamed display's role (Extend/Primary/Exclusive) instead of
  the confusing physical-monitor-only framing; notes the headless case. Identity help spells out the
  actual behavior (stable per-client identity → the desktop reapplies that client's scaling/resolution
  on reconnect) + what Shared / Per-client / Per-client+resolution each do.
- Cap description/help width at max-w-prose so long help text isn't a full-viewport line on large screens.
- Mobile bottom nav: 8 flat tabs were too cramped → 4 pinned tabs + a "More" tab whose sheet holds the
  rest (Performance/Logs/Pairing/Settings), "More" highlighted when the active route is in the overflow.
- More breathing room under the "Preset" heading.

web tsc + biome + vite build green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web/messages/en.json

@@ -9,6 +9,7 @@
 	"nav_pairing": "Pairing",
 	"nav_library": "Library",
 	"nav_settings": "Settings",
+	"nav_more": "More",
 	"status_title": "Live status",
 	"status_video": "Video",
 	"status_audio": "Audio",
@@ -87,7 +88,7 @@
 	"display_preset_current": "Active",
 	"display_preset_soon": "coming soon",
 	"display_keep_alive_help": "Off tears the display down as soon as the client disconnects. Keep it alive (and, on gamescope, its game) so a quick reconnect resumes instantly instead of rebuilding.",
-	"display_topology_help": "What happens to the host's physical monitors while streaming.",
+	"display_topology_help": "How the streamed display fits into the host's desktop. Extend: an extra screen alongside your monitors. Primary: the streamed display becomes the primary output, your monitors kept. Exclusive: the streamed display is the sole output — physical monitors are disabled while streaming and restored after. On a headless host it just sets whether the streamed display is the primary.",
 	"display_conflict": "When another client connects",
 	"display_conflict_help": "What happens if a second client connects while one is already streaming and asks for a different resolution.",
 	"display_conflict_separate": "Own display",
@@ -95,7 +96,7 @@
 	"display_conflict_join": "Share view",
 	"display_conflict_reject": "Busy — reject",
 	"display_identity": "Per-client identity",
-	"display_identity_help": "Give each client a stable display so the desktop remembers its per-monitor settings (e.g. scaling).",
+	"display_identity_help": "Whether the streamed display carries a stable per-client identity, so the host's desktop remembers that client's per-monitor settings (scaling, resolution) and reapplies them when it reconnects. Shared: one identity for everyone. Per client: each device keeps its own. Per client + resolution: a device keeps separate settings per resolution it connects at.",
 	"display_identity_shared": "Shared",
 	"display_identity_per_client": "Per client",
 	"display_identity_per_client_mode": "Per client + resolution",