Fix meeting summaries: long transcripts overflowed the LLM context

Reproduced on the 68-min meeting: the timestamped transcript filled
the whole 32k window (prompt_eval 32451), gemma4 hit the length limit
and returned an EMPTY answer (done_reason=length) — which the server
wrote as an empty summary.md and marked "done". Fixes:

- num_ctx 32768 -> 65536 and transcript cap 90k -> 100k chars (env
  OLLAMA_NUM_CTX / TRANSCRIPT_MAX_CHARS); ~33k tokens now fit with
  plenty of room for the answer
- _ollama_chat treats an empty response as an ERROR (with done_reason
  and prompt_eval in the message) instead of producing a done-with-empty
  summary
- truncated transcripts get a note appended to the summary
- startup recovery: a container restart resets stale "pending" statuses
  so the UI can never stick on "wird erstellt" from dead threads
- phone: the summary/agenda poll survives transient fetch errors
  (previously one network hiccup stopped the poll forever)

android/app/src/main/java/com/meetrec/android/LibraryScreen.kt

@@ -205,17 +205,20 @@ private fun LibraryDetail(
         }
     }
 
-    // poll while the server is generating (summary + agenda run via Ollama)
-    LaunchedEffect(meta?.summary, meta?.agendaStatus) {
-        val m = meta ?: return@LaunchedEffect
+    // poll while the server is generating (summary + agenda run via Ollama);
+    // transient fetch errors must not stop the poll — the UI would stick on
+    // "wird erstellt" forever
+    LaunchedEffect(item) {
+        val m0 = (item as? LibraryItem.Server)?.meta ?: return@LaunchedEffect
+        var m = m0
         val url = storageUrl.trim().trimEnd('/')
-        if (m.summary == "pending" || m.agendaStatus == "pending") {
+        while (m.summary == "pending" || m.agendaStatus == "pending") {
             delay(5_000)
             try {
-                meta = withContext(Dispatchers.IO) {
-                    StorageClient.fetchMeta(url, m.id)
-                }
+                m = withContext(Dispatchers.IO) { StorageClient.fetchMeta(url, m.id) }
+                meta = m
             } catch (_: Exception) {
+                // network hiccup — retry on the next loop iteration
             }
         }
     }