Expand Statsbomb case study with detailed DSL examples and phase-driven architecture

- Add 6 comprehensive soccer rules (pass completion, carry, counter-attack, possession, tiki-taka, turnover)
- Add 6 American football rules (snap completion, offensive drive, red zone, third-down, drive stall, scoring drive)
- Replace simple data flow diagram with functional pipeline showing map/reduce/overlap transformations
- Rewrite event dependency graph as phase-driven state machine (defense/loose/carry phases)
- Add metadata temporal stages section (competition schedules, matchday lineups, entity streaming)
- Improve Mermaid diagram text spacing using multi-line quoted syntax instead of <br/> tags
- Fix terminology: analysts → collectors (correct role)
- Add htmlLabels documentation comment in astro.config.mjs

Author: saadshahd

astro.config.mjs

@@ -35,6 +35,7 @@ export default defineConfig({
           tertiaryColor: '#FEF3C7',          // Warm amber (atomic nodes)
         },
         flowchart: {
+          htmlLabels: true,          // Enable HTML in node labels (for <br/> line breaks)
           titleTopMargin: 12,        // Space above main diagram title
           subGraphTitleMargin: {     // Space around subgraph titles
             top: 12,