Remove Great Bear station (not available on weather.gov)

After extensive testing, Great Bear does not have a weather.gov station ID.
Tested variations: YCGBR, GBRM, GBR, GRBT, YCGRE, YCGRT, GBEAR - none exist.

Great Bear data on mtavalanche.com comes from a private station that
doesn't report to the National Weather Service network.

Removed from dropdown and added info note explaining unavailability.

Working stations:
- YC Timberline (YCTIM) ✓
- YC Andesite (YCAND) ✓
- YC American Spirit (YCAMS) ✓
- YC Base (YCBAS) ✓

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

app.py

@@ -432,11 +432,11 @@ with gr.Blocks(title="Weather Station Data Analyzer") as demo:
                 ("Yellowstone Club - Andesite", "YCAND"),
                 ("Yellowstone Club - American Spirit", "YCAMS"),
                 ("Yellowstone Club - Base", "YCBAS"),
-                ("Yellowstone Club - Great Bear", "YCGBR"),
                 ("Bozeman Airport", "KBZN"),
                 ("Salt Lake City", "KSLC")
             ],
-            value="YCTIM"
+            value="YCTIM",
+            info="Note: Great Bear not available (no weather.gov station ID)"
         )
         hours = gr.Number(
             label="Hours of Data",