feat: two-tier status bar, one glance line with the detail behind an info popover

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

src/status_text.hpp

@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: MIT
+#pragma once
+
+#include <cstddef>
+#include <cstdint>
+#include <string>
+
+namespace udpscope {
+
+/// Everything either tier of the status bar shows, gathered once per frame by the tick so the
+/// two cannot disagree. No GTK here on purpose: this is the one part of the status bar that
+/// can be reasoned about as text.
+struct StatusSnapshot {
+  /// One word from the fixed set: "live", "paused", "armed", "capturing", "event held",
+  /// "disarmed". It is a word from a *fixed* set because the bar sits directly above the plot
+  /// and a field whose width tracked the stream would relayout it every frame.
+  const char* state_word = "live";
+  /// The long prose the old single-line bar carried, kept for the detail string and the dump.
+  std::string state_detail;
+
+  bool connected = false;
+  bool have_config = false;
+  bool trigger_on = false;
+
+  /// Already collapsed to one figure or a range by the caller, without the "rate " prefix.
+  std::string rate_text;
+  double stored_rate_hz = 0.0;
+  double declared_rate_hz = 0.0;
+
+  /// Pre-formatted by ui.cpp's format_window(), which the window control and the Fit notices
+  /// also use, so it stays there rather than moving here.
+  std::string window_text;
+
+  std::uint64_t packets = 0;
+  std::uint64_t frames = 0;
+  std::uint64_t gaps = 0;
+  std::size_t signals = 0;
+  std::size_t channels = 0;
+  int plot1_traces = 0;
+  std::size_t plot1_samples = 0;
+  double buffer_mb = 0.0;
+  double span_s = 0.0;
+  std::uint64_t time_stride = 1;
+  bool have_event = false;
+  double since_event_s = 0.0;
+  int reconnects = 0;
+};
+
+/// The bar: "live · 10.0 kS/s · 2 s window", plus " · event 4.2 s ago" in trigger mode and
+/// nothing else ever. The badge glyph is a separate widget and is not part of this string.
+std::string format_glance(const StatusSnapshot& s);
+
+/// The popover's prose and the exit dump's line, field for field as the old single-line bar
+/// wrote it. CLAUDE.md asserts those fields are read out of the dump, so the field names and
+/// their order must not change without updating it.
+std::string format_detail(const StatusSnapshot& s);
+
+/// A sample rate as "10.0 kS/s". Moved here from ui.cpp, which still calls it.
+std::string format_rate(double hz);
+
+/// An elapsed time, stepping to a coarser unit rather than growing digits, so its width
+/// cannot track the stream. Moved here from ui.cpp.
+std::string format_elapsed(double seconds);
+
+}  // namespace udpscope