feat: complete prediction UI feedback tasks (11.2, 11.4, 11.5)

- Implement disagreement visual highlighting with distinct colors
  - Yellow highlight for 'missed_by_human' predictions
  - Orange for 'label_mismatch' disagreements
  - Warning icon on disagreement markers
- Add click-to-convert prediction feedback
  - Click disagreement predictions to create span annotations
  - Auto-fill with predicted label and times
  - Set source as 'model_confirmed' or 'model_corrected'
- Add dismiss action for false positive predictions
  - Alt+Click or Ctrl+Click to dismiss predictions
  - Saves negative annotation with label 'O'
  - Records original prediction in model_prediction field
- Filter predictions when 'Show only disagreements' is enabled

openspec/changes/line-rectangle-annotations/proposal.md

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+## Why
+
+The current line drawing implementation uses an SVG overlay (`SvgOverlay.tsx`) positioned on top of the lightweight-charts canvas. This creates a disconnect — lines don't participate in chart autoscaling, coordinate conversion is duplicated outside the chart library, and the rendering layer is split between SVG and canvas. Lightweight-charts natively supports drawing primitives via the `ISeriesPrimitive` API, and the project already has a `TrendLine` plugin in `src/plugins/trend-line.ts` (unused) and uses `SpanRectanglePrimitive` for span annotations. Migrating line drawing to the native plugin system and adding rectangle annotations will unify the rendering approach, improve performance, and enable consistent interaction patterns.
+
+## What Changes
+
+- **BREAKING**: Remove SVG overlay line drawing (`SvgOverlay.tsx`) and replace with lightweight-charts `TrendLine` plugin-based rendering
+- Implement interactive two-click line drawing using chart's native `subscribeClick()` and `subscribeCrosshairMove()` events instead of SVG pointer events
+- Add a new rectangle annotation tool based on the lightweight-charts `RectangleDrawingTool` plugin pattern (two-click to define opposite corners)
+- Add "rectangle" tool mode to the Toolbox alongside existing line/span/label tools
+- Store rectangle annotations in the database with `label_type: "rectangle"` and geometry containing `{startTime, startPrice, endTime, endPrice}`
+- Update line editing (drag endpoints) and deletion to work through the plugin system instead of SVG hit detection
+- Add preview rendering during drawing for both lines and rectangles (using crosshair move events)
+
+## Capabilities
+
+### New Capabilities
+- `rectangle-annotation`: Two-click rectangle drawing tool using lightweight-charts ISeriesPrimitive, with preview during drawing, persistence, editing, and deletion
+
+### Modified Capabilities
+- `annotation-tools`: Line drawing changes from SVG overlay to lightweight-charts TrendLine plugin; line tool mode interaction moves from SVG events to chart subscribeClick/subscribeCrosshairMove; line editing and deletion use plugin-based hit detection instead of SVG proximity calculation
+
+## Impact
+
+- **Frontend components**: `SvgOverlay.tsx` removed or gutted; `CandleChart.tsx` updated to manage TrendLine primitives; `Toolbox.tsx` gains rectangle tool button
+- **Plugins**: `src/plugins/trend-line.ts` enhanced with interactive drawing support (click handlers, preview); new `src/plugins/rectangle-drawing.ts` added
+- **API**: Existing annotation endpoints used as-is; rectangle annotations use the same `annotations` table with `label_type: "rectangle"` and `geometry` JSON
+- **Database**: No schema changes — rectangles use the existing `geometry` column pattern (same as lines)
+- **Dependencies**: No new dependencies — uses lightweight-charts APIs already in use