Fix feed OOM: cap follow feed at 30, WebKit software rendering, dedup notification fetches

- followNotes capped at 30 (was 80) — following feed was rendering 2.7x more
  notes than global, causing 4GB+ spike on media-heavy follow content
- fetchFollowFeed limit 80→30 to match
- WEBKIT_FORCE_SOFTWARE_RENDERING=1 replaces WEBKIT_DISABLE_COMPOSITING_MODE=1
  (compositing mode killed Wayland path → blank window on Hyprland)
- HardwareAccelerationPolicy::Never → OnDemand (Never also caused blank screen)
- set_enable_page_cache(false) — SPA never navigates, bfcache is pure waste
- Removed duplicate fetchNotifications calls on login (was firing 3x in 8s)
- First notification poll delayed 8s→90s to avoid competing with feed load
- Result: login 3600MB→453MB, following feed crash→737MB, plateau at ~950MB

src-tauri/src/lib.rs

@@ -436,7 +436,7 @@ pub fn run() {
                 }
             }
 
-            // ── WebKit GPU workaround for Linux (webkit2gtk 2.50+ black screen) ──
+            // ── WebKit memory tuning for Linux (webkit2gtk) ──────────────────
             #[cfg(target_os = "linux")]
             {
                 let main_window = app.get_webview_window("main").unwrap();
@@ -444,15 +444,20 @@ pub fn run() {
                     use webkit2gtk::{CacheModel, SettingsExt, WebContextExt, WebViewExt};
                     let wv = webview.inner();
                     if let Some(settings) = wv.settings() {
+                        // OnDemand: use GPU if available, CPU fallback otherwise.
+                        // HardwareAccelerationPolicy::Never + WEBKIT_DISABLE_COMPOSITING_MODE=1
+                        // both kill the Wayland compositor path → blank window on Hyprland.
+                        // WEBKIT_FORCE_SOFTWARE_RENDERING=1 (set in main.rs) forces CPU
+                        // rasterization without disrupting the Wayland surface.
                         settings.set_hardware_acceleration_policy(
-                            webkit2gtk::HardwareAccelerationPolicy::Never,
+                            webkit2gtk::HardwareAccelerationPolicy::OnDemand,
                         );
+                        // Vega is a SPA — no back/forward navigation, page cache is pure waste.
+                        settings.set_enable_page_cache(false);
                     }
-                    // Minimize WebKit's in-memory content cache (decoded images, scripts, etc.)
-                    // Default is WebBrowser which caches aggressively. DocumentViewer is the
-                    // minimum: no back/forward page cache, smallest memory footprint.
-                    // This is safe for Vega — it's a single-page app, never navigates between pages.
                     if let Some(ctx) = wv.context() {
+                        // DocumentViewer: smallest in-memory content cache footprint.
+                        // No back/forward page cache, only the active document cached.
                         ctx.set_cache_model(CacheModel::DocumentViewer);
                     }
                 }).ok();

src-tauri/src/main.rs

@@ -7,12 +7,11 @@ fn main() {
     #[cfg(target_os = "linux")]
     {
         std::env::set_var("WEBKIT_DISABLE_DMABUF_RENDERER", "1");
-        // Required on Linux with large RAM/swap: WebKitGTK compositor pre-allocates
-        // ~25% of total virtual memory (RAM+swap) for its tile cache. On a 14GB RAM +
-        // 19GB swap system this is ~4 GB, filling all RAM and freezing the machine.
-        // Software rendering is slower but memory-safe. Fix: reduce swap or implement
-        // virtual scrolling (fewer compositor layers).
-        std::env::set_var("WEBKIT_DISABLE_COMPOSITING_MODE", "1");
+        // Force CPU-only rasterization while keeping the Wayland compositor path intact.
+        // WEBKIT_DISABLE_COMPOSITING_MODE=1 kills the GPU process but also breaks Wayland
+        // rendering (blank window on Hyprland). WEBKIT_FORCE_SOFTWARE_RENDERING=1 cuts GPU
+        // RAM without disrupting the Wayland surface — the right tradeoff on this machine.
+        std::env::set_var("WEBKIT_FORCE_SOFTWARE_RENDERING", "1");
     }
 
     vega_lib::run()