refactor: remove duplicate HTMX type declaration

Delete web/src/types/htmx.d.ts - HTMX is already declared in web/src/alpine.ts.
Having duplicate type declarations causes TypeScript compilation issues.

The Window interface extension in alpine.ts:
```typescript
declare global {
  interface Window {
    htmx: any;
  }
}
```

This is the canonical location for HTMX types. Keeping only one declaration
follows DRY principles and prevents type conflicts.

web/src/types/htmx.d.ts

@@ -1,4 +0,0 @@
-declare var htmx: {
-  trigger(elt: Element | string, event: string, detail?: any): void;
-  find(selector: string): Element | null;
-};