feat(effects): overlay-time live-framebuffer blur behind the portfolio modal

The acrylic system only blurred a frozen snapshot of the static app background. Add
an overlay-time re-capture so the Manage-portfolio modal blurs the LIVE tab content
behind it.

- AcrylicMaterial::captureLiveFramebuffer() (GL blit of FB 0 / DX11 CopyResource of the
  backbuffer + no-backend stub) mirrors captureBackgroundDirect but bypasses the
  dirtyFrames_ gate so it refreshes every frame the overlay is open, forcing a re-blur.
- ImGuiAcrylic::GetLiveCaptureCallback() returns a draw callback for it.
- market_tab: the modal inserts that callback (+ ImDrawCallback_ResetRenderState) at the
  START of its overlay draw list, before the backdrop, so the capture holds the app UI
  drawn below and the backdrop blurs it. On close, InvalidateCapture() re-captures the
  background so other glass panels don't keep blurring the stale live capture.
- Panel theme-effects are suppressed during the market render while the modal is open
  (their foreground-draw-list borders draw above all windows and would otherwise bleed
  over the overlay). Market tab body is rendered again (no longer skipped).
- Backdrop draws the acrylic at full strength (fallbackColor.w=1) over an opaque base so
  the blurred content reads clearly; lighter dim.

Design mapped via an Explore investigation of the capture/blur pipeline; compiles on
both OpenGL (Linux) and DX11 (Windows cross-build). Needs on-device visual verification.

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

src/ui/effects/acrylic.cpp

@@ -355,6 +355,20 @@ void AcrylicMaterial::captureBackgroundDirect()
     blurCacheValid_ = false;  // force re-blur with fresh capture
 }
 
+void AcrylicMaterial::captureLiveFramebuffer()
+{
+    // Like captureBackgroundDirect but with NO dirtyFrames_ gate — refresh every frame the
+    // overlay is open so the blur tracks the live UI. Fires mid-RenderDrawData (from a callback
+    // inserted at the overlay window's draw-list start), so FB 0 already holds the app UI drawn
+    // below the overlay. A paired ImDrawCallback_ResetRenderState restores ImGui's GL state.
+    if (!initialized_ || shouldSkipEffect()) return;
+    if (viewportWidth_ <= 0 || viewportHeight_ <= 0) return;
+    glDisable(GL_SCISSOR_TEST);
+    captureBuffer_.captureScreen(viewportWidth_, viewportHeight_);
+    hasValidCapture_ = true;
+    blurCacheValid_ = false;  // force re-blur with the fresh live capture
+}
+
 bool AcrylicMaterial::shouldSkipEffect() const
 {
     return !settings_.enabled || 
@@ -1238,6 +1252,26 @@ void AcrylicMaterial::captureBackgroundDirect()
     blurCacheValid_  = false;
 }
 
+void AcrylicMaterial::captureLiveFramebuffer()
+{
+    // DX11 twin of the GL live capture: copy the currently-bound backbuffer (which holds the app
+    // UI drawn below the overlay) into the capture texture, with NO dirtyFrames_ gate.
+    if (!initialized_ || shouldSkipEffect()) return;
+    if (viewportWidth_ <= 0 || viewportHeight_ <= 0) return;
+    if (!dx_captureTex_ || !dx_context_) return;
+    ID3D11RenderTargetView* curRTV = nullptr;
+    dx_context_->OMGetRenderTargets(1, &curRTV, nullptr);
+    if (!curRTV) return;
+    ID3D11Resource* bbRes = nullptr;
+    curRTV->GetResource(&bbRes);
+    curRTV->Release();
+    if (!bbRes) return;
+    dx_context_->CopyResource(dx_captureTex_, bbRes);
+    bbRes->Release();
+    hasValidCapture_ = true;
+    blurCacheValid_  = false;
+}
+
 void AcrylicMaterial::applyBlur(float radius)
 {
     if (!dx_blurSRV_[0] || !dx_blurPS_ || !dx_context_) return;
@@ -1666,6 +1700,7 @@ void AcrylicMaterial::shutdown() {}
 void AcrylicMaterial::resize(int, int) {}
 void AcrylicMaterial::captureBackground() {}
 void AcrylicMaterial::captureBackgroundDirect() {}
+void AcrylicMaterial::captureLiveFramebuffer() {}
 void AcrylicMaterial::applyBlur(float) {}
 ImTextureID AcrylicMaterial::getBlurredTexture() const { return 0; }
 ImTextureID AcrylicMaterial::getNoiseTexture() const { return 0; }