fix: compact timestamps, historical alias resolution, wider ts column

- Timestamps now show "Jun 28 10:58" for older messages (dropped
  "Yesterday" which overflowed the fixed-width column)
- Timestamp column widened from 52px to 72px to fit date+time
- state_snapshot now includes known_peers (historically seen, not
  currently connected) so the UI can resolve aliases in history
- MessagePane aliasFor falls back to knownPeers map

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/src/store/index.ts

@@ -29,6 +29,7 @@ interface WasteState {
 
   // peers
   connectedPeers: PeerInfo[]
+  knownPeers: Record<string, string> // id → alias for historical peers
 
   // chat — keyed by room
   messages: Record<string, ChatMessage[]>
@@ -87,6 +88,7 @@ export const useWaste = create<WasteState>((set, get) => ({
   networks: [],
   activeNetworkId: null,
   connectedPeers: [],
+  knownPeers: {},
   messages: {},
   historyCutoff: {},
   activeRoom: 'general',
@@ -215,6 +217,8 @@ export const useWaste = create<WasteState>((set, get) => ({
     switch (msg.type) {
       case 'state_snapshot': {
         const networks = msg.networks ?? []
+        const knownPeers: Record<string, string> = {}
+        for (const p of msg.known_peers ?? []) knownPeers[p.id] = p.alias
         set({
           masterAlias: msg.master_alias ?? null,
           masterId: msg.master_id ?? null,
@@ -222,6 +226,7 @@ export const useWaste = create<WasteState>((set, get) => ({
           networks,
           connectedPeers: msg.connected_peers ?? [],
           activeNetworkId: networks[0]?.network_id ?? null,
+          knownPeers,
         })
         break
       }