feat: new preset, looper recorder, IR display improvements

- New Preset button: finds first empty slot, saves with default name
- Looper/Recorder tab: Record/Stop via arecord backend, list captures, play back
- Rig: shows loaded IR name more clearly + quick-link buttons to browse IRs/Models
- Backend: capture/start, capture/stop, captures API endpoints with file serve

src/web/server.py

@@ -16,6 +16,7 @@ import json
 import os
 import logging
 import time
+import datetime
 from contextlib import asynccontextmanager
 from dataclasses import dataclass, field
 from pathlib import Path
@@ -892,6 +893,75 @@ class WebServer:
                     },
                 )
 
+        # ── Audio capture (looper/recorder) ──────────────────────
+        _capture_process = None
+        _capture_path = None
+
+        @app.post("/api/capture/start")
+        async def capture_start():
+            """Start recording audio to a WAV file via arecord."""
+            nonlocal _capture_process, _capture_path
+            import subprocess, datetime
+            captures_dir = Path.home() / ".pedal" / "captures"
+            captures_dir.mkdir(parents=True, exist_ok=True)
+            ts = datetime.datetime.now().strftime("%Y%m%d_%H%M%S")
+            path = captures_dir / f"capture_{ts}.wav"
+            try:
+                _capture_process = subprocess.Popen(
+                    ["arecord", "-f", "S16_LE", "-r", "48000", "-c", "2", str(path)],
+                    stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL,
+                )
+                _capture_path = path
+                return {"ok": True, "path": str(path), "filename": path.name}
+            except Exception as e:
+                raise HTTPException(status_code=500, detail=str(e))
+
+        @app.post("/api/capture/stop")
+        async def capture_stop():
+            """Stop the current recording."""
+            nonlocal _capture_process, _capture_path
+            if _capture_process is None:
+                raise HTTPException(status_code=400, detail="No active recording")
+            try:
+                _capture_process.terminate()
+                _capture_process.wait(timeout=5)
+            except Exception:
+                _capture_process.kill()
+            name = _capture_path.name if _capture_path else "unknown"
+            _capture_process = None
+            _capture_path = None
+            return {"ok": True, "filename": name}
+
+        @app.get("/api/captures")
+        async def list_captures():
+            """List saved captures."""
+            captures_dir = Path.home() / ".pedal" / "captures"
+            if not captures_dir.is_dir():
+                return {"captures": []}
+            files = sorted(captures_dir.glob("*.wav"), key=lambda f: f.stat().st_mtime, reverse=True)
+            return {
+                "captures": [
+                    {
+                        "name": f.name,
+                        "path": str(f),
+                        "size": f.stat().st_size,
+                        "size_display": f"{f.stat().st_size / 1024:.0f} KB" if f.stat().st_size < 1024*1024 else f"{f.stat().st_size / (1024*1024):.1f} MB",
+                        "created": datetime.datetime.fromtimestamp(f.stat().st_mtime).isoformat(),
+                    }
+                    for f in files
+                ]
+            }
+
+        @app.get("/api/captures/{filename}")
+        async def serve_capture(filename: str):
+            """Serve a captured WAV file for download/playback."""
+            from fastapi.responses import FileResponse
+            captures_dir = Path.home() / ".pedal" / "captures"
+            file_path = captures_dir / filename
+            if not file_path.exists() or not file_path.is_file():
+                raise HTTPException(status_code=404, detail="Capture not found")
+            return FileResponse(str(file_path), media_type="audio/wav", filename=filename)
+
         # ── Tonehub API alias routes ─────────────────────────────
         # These are direct aliases for Tone3000 search, providing a
         # simpler /api/tonehub/search path for the web UI.