feat: HUD album/track + Control/Hydra deeplinks

Context: the user noticed the auto-launched browser tab landed on the
landing page (just two cards saying 'Control' / 'Hydra') instead of the
control surface with all 11 tabs (Transport, Album, Mixer, Steps, Acid,
Harmony, Kicks, FX, Sends, LFO, Tricks). And while sclang was emitting
/sync/album, /sync/melody, /sync/synthdef, oscope-of received them but
never showed them — the HUD only had FPS + mode.

Approach: launcher's auto-open now goes straight to /control/, with a
second 'Hydra' button in the popover for the visual canvas page. In
oscope-of, drawHud() gets a top-left info box that reads OscClient
state and prints ALBUM / MELODY / SYNTH / BPM / BEAT lines plus a
beat-pulse dot driven by kick amplitude. Box is drawn semi-transparent
so it survives the post-fx chain without blocking the visualizers.

Changes:
- launcher/ProcessManager.swift :
  * autoOpenBrowser now opens /control/ instead of /
  * new openHydra() method for the second deeplink
- launcher/MenuBarContent.swift : the single 'Open in browser' button
  becomes two — 'Control' (slider icon) and 'Hydra' (waveform icon),
  both disabled until the web server is running
- oscope-of/ofApp.cpp drawHud() : adds top-left info box with the
  five lines from osc_.album()/melody()/synthdef()/bpm()/beat(),
  semi-transparent black backdrop with a dim cyan border, beat dot
  in the top-right corner of the box that pulses with kick amp.
  Empty-string fields are skipped so the box is small at startup
  before sclang has emitted anything

Impact: the operator now sees the live state of the sound_algo engine
overlaid on the visualizer at all times, without switching to the
browser. The browser tab opens directly on the working surface.
Smoke-tested end-to-end on the Big Sur Intel MBP.

TODO from this session's question — not done yet, follow-up commits :
  - SwiftUI menubar submenu listing albums and tracks
  - Album sequencer / playlist mode
  - MIDI keyboard / pad mapping to ~kk / ~mm / ~ff / ~cc / ~p
  - Hantek 6022BL USB driver wiring (firmware + entitlements)

launcher/Sources/AVLiveLauncher/MenuBarContent.swift

@@ -38,7 +38,11 @@ struct MenuBarContent: View {
 
             HStack {
                 Button(action: processManager.openBrowser) {
-                    Label("Open in browser", systemImage: "safari")
+                    Label("Control", systemImage: "slider.horizontal.3")
+                }
+                .disabled(!processManager.webRunning)
+                Button(action: processManager.openHydra) {
+                    Label("Hydra", systemImage: "waveform")
                 }
                 .disabled(!processManager.webRunning)
                 Spacer()

launcher/Sources/AVLiveLauncher/ProcessManager.swift

@@ -114,7 +114,7 @@ final class ProcessManager: ObservableObject {
         if autoOpenBrowser {
             DispatchQueue.main.asyncAfter(deadline: .now() + 3.5) { [weak self] in
                 guard let self = self else { return }
-                if let url = URL(string: "http://localhost:\(self.webPort)/") {
+                if let url = URL(string: "http://localhost:\(self.webPort)/control/") {
                     NSWorkspace.shared.open(url)
                 }
             }
@@ -167,7 +167,13 @@ final class ProcessManager: ObservableObject {
     }
 
     func openBrowser() {
-        if let url = URL(string: "http://localhost:\(webPort)/") {
+        if let url = URL(string: "http://localhost:\(webPort)/control/") {
+            NSWorkspace.shared.open(url)
+        }
+    }
+
+    func openHydra() {
+        if let url = URL(string: "http://localhost:\(webPort)/hydra/") {
             NSWorkspace.shared.open(url)
         }
     }

oscope-of/src/ofApp.cpp

@@ -291,12 +291,55 @@ void ofApp::draw() {
 
 void ofApp::drawHud() {
     ofPushStyle();
+
+    // Bottom-left : FPS + mode
     ofSetColor(180, 220, 200, 220);
     ofDrawBitmapString("FPS: " + ofToString(ofGetFrameRate(), 1),
                        12, ofGetHeight() - 28);
     ofDrawBitmapString(std::string("Mode: ") + modeName(mode_) +
         (postFxEnabled_ ? "  [fx ON]" : "  [fx OFF]"),
         12, ofGetHeight() - 12);
+
+    // Top-left : sound_algo state from /sync/* (album, melody, synthdef,
+    // bpm, beat). Boxed background so it stays readable over any visual.
+    const std::string& album = osc_.album();
+    const std::string& melody = osc_.melody();
+    const std::string& synthdef = osc_.synthdef();
+    const float bpm = osc_.bpm();
+    const int beat = osc_.beat();
+    const float kick = osc_.amp("kick");
+
+    std::vector<std::string> lines;
+    if (!album.empty())    lines.push_back("ALBUM   " + album);
+    if (!melody.empty())   lines.push_back("MELODY  " + melody);
+    if (!synthdef.empty()) lines.push_back("SYNTH   " + synthdef);
+    lines.push_back("BPM     " + ofToString(bpm, 1) +
+                    "   BEAT " + ofToString(beat));
+
+    if (!lines.empty()) {
+        const int padding = 8;
+        const int lineH = 14;
+        const int boxW = 280;
+        const int boxH = static_cast<int>(lines.size()) * lineH + padding * 2;
+        ofSetColor(0, 0, 0, 150);
+        ofDrawRectangle(12, 12, boxW, boxH);
+        ofSetColor(140, 200, 255, 60);
+        ofNoFill();
+        ofDrawRectangle(12, 12, boxW, boxH);
+        ofFill();
+        for (std::size_t i = 0; i < lines.size(); ++i) {
+            ofSetColor(220, 230, 240, 230);
+            ofDrawBitmapString(lines[i],
+                               12 + padding,
+                               12 + padding + 11 + static_cast<int>(i) * lineH);
+        }
+        // Beat indicator dot pulses on each beat (uses kick amp as proxy)
+        const float pulse = std::min(1.0f, kick * 2.0f);
+        ofSetColor(255, 180, 80, static_cast<int>(120 + pulse * 135.0f));
+        ofDrawCircle(12 + boxW - padding - 6, 12 + padding + 6,
+                     3.0f + pulse * 4.0f);
+    }
+
     ofPopStyle();
 }