Improve type safety: Replace any with proper types

Replace `candidate: any` with `candidate: RTCIceCandidateInit | null`:

Changes:
- api.ts poll() return type (line 366)
- rondevu.ts pollOffers() return type (line 827)
- IceCandidate interface (line 41)

Benefits:
- Better type safety and IntelliSense support
- Matches WebRTC spec (candidates can be null)
- Catches potential type errors at compile time
- Clearer API contracts for consumers

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/api.ts

@@ -38,7 +38,7 @@ export interface Service {
 }
 
 export interface IceCandidate {
-    candidate: RTCIceCandidateInit
+    candidate: RTCIceCandidateInit | null
     createdAt: number
 }
 
@@ -363,7 +363,7 @@ export class RondevuAPI {
         iceCandidates: Record<
             string,
             Array<{
-                candidate: any
+                candidate: RTCIceCandidateInit | null
                 role: 'offerer' | 'answerer'
                 peerId: string
                 createdAt: number

src/rondevu.ts

@@ -824,7 +824,7 @@ export class Rondevu {
             answeredAt: number
         }>
         iceCandidates: Record<string, Array<{
-            candidate: any
+            candidate: RTCIceCandidateInit | null
             role: 'offerer' | 'answerer'
             peerId: string
             createdAt: number