feat: Overhaul client-side navigation and clean up project

- Implement a unified SPA routing system in nav.js, removing all legacy and conflicting navigation scripts (router.js, inject-nav.js, fix-nav.js).
- Refactor dashboard.js to delegate all navigation handling to the new nav.js module.
- Create new modular JS files (auth.js, personal-player.js, logger.js) to improve code organization.
- Fix all navigation-related bugs, including guest access and broken footer links.
- Clean up the project root by moving development scripts and backups to a dedicated /dev directory.
- Add a .gitignore file to exclude the database, logs, and other transient files from the repository.

convert_to_opus.py

@@ -1,39 +0,0 @@
-# convert_to_opus.py — Default voice pipeline: bandpass + compressor + limiter + gate
-
-import subprocess
-import os
-
-def convert_to_opus(input_path, output_path):
-    if not os.path.exists(input_path):
-        raise FileNotFoundError(f"Input file not found: {input_path}")
-
-    filters = [
-        "highpass=f=400",             # low-cut below 400 Hz
-        "lowpass=f=12000",            # high-cut above 12 kHz
-        "acompressor=threshold=-18dB",
-        "alimiter=limit=-1dB",
-        "agate=threshold=0.02"
-    ]
-
-    cmd = [
-        "ffmpeg", "-y",
-        "-i", input_path,
-        "-af", ",".join(filters),
-        "-ac", "1",
-        "-ar", "24000",
-        "-c:a", "libopus",
-        "-b:a", "40k",
-        "-vbr", "on",
-        "-application", "voip",
-        output_path
-    ]
-
-    try:
-        subprocess.run(cmd, check=True, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
-    except subprocess.CalledProcessError as e:
-        raise RuntimeError(f"FFmpeg conversion failed: {e}")
-
-    if not os.path.exists(output_path):
-        raise RuntimeError("Conversion did not produce output.")
-
-    return output_path