fix(review): restore Agent Update Required flow, command field, axis alignment

Fixes from Jason's hands-on verification of the branch:

1. Old-agent messaging regression (this branch): a detail-request timeout
   went through the loud poison/reconnect flow, burying the ProcessDetails
   modal's 'Agent Update Required' message under a connection-error modal.
   Old agents IGNORE unknown messages (no late reply, no desync), so the
   optional per-PID endpoints now use quiet_reconnect(): swap the stream
   silently (still safe against merely-slow agents) and let the modal show
   its message. Only a failed reconnect surfaces loudly. Verified against
   a real v1.40.0 agent: message shows, session stays healthy.

2. Draw starvation (this branch): an agent that never answers get_metrics
   put the loop in fetch->timeout->poison->restart cycles that never
   reached the draw call — permanently blank TUI. The iteration now paints
   before fetching, and a second consecutive metrics timeout trips a
   circuit breaker: persistent 'Agent is not responding' error, recovery
   left to the manual/30s retry paths. Verified against a 0.9-era agent.

3. Command & Details pane blank (pre-existing on master): the minimal-
   refresh optimization dropped cmd/exe/cwd from the detail endpoint's
   ProcessRefreshKind, so process.cmd() had nothing to return. Restored
   with UpdateKind::OnlyIfNotSet — immutable values, read once per PID.
   Regression test added; journal E2E re-verified (100 entries render).

4. Scatter-plot axis misalignment: Y labels used a fixed 4-char field from
   the era when CPU times were 1000x too small; honest millisecond values
   (e.g. 136114) blew through it. Labels now right-align to the widest
   value per frame and X labels/titles share the dynamic padding.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

socktop_agent/tests/process_details.rs

@@ -87,3 +87,19 @@ async fn test_collect_journal_entries_invalid_pid() {
         }
     }
 }
+
+/// The Command & Details pane went blank when the minimal-refresh
+/// optimization dropped cmd from the detail endpoint's refresh kind.
+#[tokio::test]
+async fn test_process_metrics_include_command() {
+    let state = AppState::new();
+    let pid = std::process::id();
+    let resp = collect_process_metrics(pid, &state)
+        .await
+        .expect("collect self");
+    assert!(
+        !resp.process.command.is_empty(),
+        "command should not be empty for self (cmdline is always readable)"
+    );
+    println!("command = {}", resp.process.command);
+}