Beam desktop v0.6.0 — Cleaner UI, rate limit fixed for real, resizing window

• Removed all emojis, the header logo, and the tagline from the UI — cleaner, less "AI demo" looking.
• Replaced the "live" text/dot connection indicator with a wifi-signal-style bars icon.
• Fixed the root cause of the rate-limit errors during testing: the connect screen's 2-second status polling was sharing a bucket with the actual pairing actions, so just leaving the screen open could trip it. They're now on separate limits.
• The desktop window opens small and grows with an animation once you press Connect to Beam, instead of always being full-size.