[fix](trx-frontend-http): keep the mini views to the rig on screen

The decode SSE stream and the history behind it are not rig-scoped: every
rig's decodes reach the browser, each carrying the rig that heard it.  The
panels on the decoder tabs want that — they aggregate the whole station —
but the mini views over the waterfall caption the spectrum underneath, and
they were reading the same unfiltered histories.  A background rig copying
APRS on another band put its frames over the active rig's waterfall.  The
mode gate did not help: it reads the mode of the rig on screen, so those
frames appeared whenever that rig happened to be in PKT.

Filter each overlay on the rig it belongs to, through one shared predicate
that compares a decode's rig_id with the per-tab active rig already driving
the spectrum and the audio.  A decode that names no rig, and a session that
has not learnt its rig list yet, still show everything.

The FTx normalizer was dropping rig_id on the floor, so it now keeps it.
CW needed more than a filter: its lines accumulate character by character,
so two rigs copying at once braided their text into one unreadable line.
Lines in progress are now kept per rig.

The bar repaints in render() move into refreshDecodeBars(), which the rig
switch calls as well — otherwise the outgoing rig's frames stayed on screen
until the next state update — and which finally includes the CW bar.

Closes #49

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SyX26FCpMQxiBoC7r5K1A7
Signed-off-by: Stan Grams <sjg@haxx.space>

src/trx-client/trx-frontend/trx-frontend-http/frontend/tests/decode-flow.mjs

@@ -22,9 +22,18 @@ const BEACON = {
   packet_type: "position", crc_ok: true, lat: 54.35, lon: 18.65,
   symbol_table: "/", symbol_code: ">", rig_id: "rig-a",
 };
+// A second rig listening in the background, on its own band. Its traffic
+// belongs in the panels, which aggregate every rig, but not in the mini view,
+// which captions the spectrum of the rig on screen.
+const OTHER_RIG_VESSEL = {
+  ...VESSEL, mmsi: 244660001, vessel_name: "ELDERBERRY", callsign: "PBTY",
+  lat: 51.92, lon: 4.48, rig_id: "rig-b",
+};
 
 // AIS is what the mini view for vessels is gated on; the rig has to be on it.
-const fixture = await startWebFixture({ spectrum: true, decodes: [VESSEL, BEACON], mode: "AIS" });
+const fixture = await startWebFixture({
+  spectrum: true, decodes: [VESSEL, BEACON, OTHER_RIG_VESSEL], mode: "AIS",
+});
 const { browser, page, runtimeErrors } = await startBrowser(chromium);
 
 try {
@@ -41,11 +50,13 @@ try {
     aprs: document.getElementById("aprs-packets")?.children.length ?? 0,
     aisStatus: document.getElementById("ais-status")?.textContent ?? "",
     aprsStatus: document.getElementById("aprs-status")?.textContent ?? "",
+    otherRig: document.getElementById("ais-messages")?.textContent.includes("ELDERBERRY") ?? false,
     mapLoaded: !!window.trx.modules.map,
   }));
   assert.equal(panels.mapLoaded, false, "the map module was loaded, so this proves nothing");
   assert.ok(panels.ais > 0, `the AIS panel is empty (status: ${panels.aisStatus})`);
   assert.ok(panels.aprs > 0, `the APRS panel is empty (status: ${panels.aprsStatus})`);
+  assert.equal(panels.otherRig, true, "the AIS panel dropped the background rig's vessel");
 
   // The mini view rides over the waterfall on the radio page.
   await page.locator('.tab[data-tab="main"]').click();
@@ -56,11 +67,13 @@ try {
       shown: getComputedStyle(bar).display !== "none",
       pins: bar.querySelectorAll(".aprs-bar-pin").length,
       names: bar.textContent.includes("NEDERLAND"),
+      otherRig: bar.textContent.includes("ELDERBERRY"),
     };
   });
   assert.equal(miniView.shown, true, "the AIS mini view did not appear");
   assert.ok(miniView.pins > 0, "the mini view has no pin to follow");
   assert.equal(miniView.names, true, "the mini view does not name the vessel");
+  assert.equal(miniView.otherRig, false, "the mini view shows a background rig's vessel");
 
   // Following the pin: the map opens, on the vessel. This is the path that was
   // broken for every decoder — the module that owned the navigation had not