feat: add support for stat sheet SVG rendering

Introduces the ability to discover and render `*.sheet.svg` files.
These files can contain `<text>` elements with `${key}` templates
that reactively update based on the current journal stats.

- Add `StatSheet` type and CLI scanning logic
- Implement `SheetView` for rendering SVGs with live bindings
- Add `parseSheet` utility to extract template patterns from SVG
- Update file indexer to include `.svg` files

src/cli/completions/block-processor.ts

@@ -22,7 +22,7 @@ import {
   resolveBlockAs,
   parseSparkTableCsv,
 } from "./block-scanner.js";
-import type { SparkTableCompletion } from "./types.js";
+import type { SparkTableCompletion, StatSheet } from "./types.js";
 
 // Re-export shared pieces for convenience
 export {
@@ -41,6 +41,7 @@ export interface ProcessedBlocks {
   stats: StatDef[];
   statTemplates: StatTemplate[];
   sparkTables: SparkTableCompletion[];
+  statSheets: StatSheet[];
 }
 
 export interface BlockResult {
@@ -81,6 +82,7 @@ export function processBlocks(
     stats: [],
     statTemplates: [],
     sparkTables: [],
+    statSheets: [],
   };
 
   const stripped = content.replace(