Reduce cyclomatic complexity in database metrics collection

Extract each metric collection into separate helper functions:
- collect_database_size: Database size metrics
- collect_connection_stats: Connection pool statistics
- collect_packets_table_stats: Table-level statistics
- collect_query_performance_stats: Query performance metrics
- collect_replication_lag: Replication lag metrics

This breaks down the complexity 27 function into manageable pieces.

Co-Authored-By: Graham <noreply@anthropic.com>

lib/aprsme/telemetry/database_metrics.ex

@@ -122,20 +122,27 @@ defmodule Aprsme.Telemetry.DatabaseMetrics do
   end
 
   defp collect_database_metrics do
-    # Database size
+    collect_database_size()
+    collect_connection_stats()
+    collect_packets_table_stats()
+    collect_query_performance_stats()
+    collect_replication_lag()
+  rescue
+    e ->
+      Logger.debug("Error collecting PostgreSQL metrics: #{inspect(e)}")
+  end
+
+  defp collect_database_size do
     case Aprsme.Repo.query("SELECT pg_database_size(current_database()) as size") do
       {:ok, %{rows: [[size]]}} ->
-        :telemetry.execute(
+        :telemetry.execute([:aprsme, :postgres, :database], %{size_bytes: size}, %{})
-          [:aprsme, :postgres, :database],
-          %{size_bytes: size},
-          %{}
-        )
 
       _ ->
         :ok
     end
+  end
 
-    # Connection stats
+  defp collect_connection_stats do
     case Aprsme.Repo.query("""
            SELECT
              count(*) as total,
@@ -162,8 +169,9 @@ defmodule Aprsme.Telemetry.DatabaseMetrics do
       _ ->
         :ok
     end
+  end
 
-    # Table stats for packets table
+  defp collect_packets_table_stats do
     case Aprsme.Repo.query("""
            SELECT
              n_live_tup as live_tuples,
@@ -195,8 +203,9 @@ defmodule Aprsme.Telemetry.DatabaseMetrics do
       _ ->
         :ok
     end
+  end
 
-    # Query performance stats
+  defp collect_query_performance_stats do
     case Aprsme.Repo.query("""
            SELECT
              sum(calls) as total_calls,
@@ -221,26 +230,20 @@ defmodule Aprsme.Telemetry.DatabaseMetrics do
       _ ->
         :ok
     end
+  end
 
-    # Replication lag (if applicable)
+  defp collect_replication_lag do
     case Aprsme.Repo.query("""
            SELECT
              extract(epoch from (now() - pg_last_xact_replay_timestamp()))::int as lag_seconds
            WHERE pg_is_in_recovery()
          """) do
       {:ok, %{rows: [[lag]]}} when not is_nil(lag) ->
-        :telemetry.execute(
+        :telemetry.execute([:aprsme, :postgres, :replication], %{lag_seconds: lag}, %{})
-          [:aprsme, :postgres, :replication],
-          %{lag_seconds: lag},
-          %{}
-        )
 
       _ ->
         :ok
     end
-  rescue
-    e ->
-      Logger.debug("Error collecting PostgreSQL metrics: #{inspect(e)}")
   end
 
   def collect_pgbouncer_metrics do