Add DemoCraftClient for complete offline demo mode

- DemoCraftClient in demo.py: duck-typed CraftClient replacement with
  8 canned satellites, synthetic pass predictions, and time-varying LEO
  arcs that drive real AOS/TCA/LOS pass events to the camera overlay
- Fix sky map EL signal fidelity: snap _el to _target_el at sweep start
  so 2D scans compute correct per-row RSSI (was using stale elevation)
- Branch on demo_mode in app.py _setup_craft_client() to inject
  DemoCraftClient instead of the HTTP CraftClient
- Add test_demo_craft.py: 5 tests exercising search, passes, tracking,
  and WAITING state through the full TUI without mocks
- Update take_screenshots.py to cover all 8 screens (dashboard, control,
  craft search, craft tracking, signal, system, console, camera)

tui/scripts/take_screenshots.py

@@ -1,21 +1,31 @@
-"""Take screenshots of all TUI screens in demo mode for documentation."""
+"""Take screenshots of all TUI screens in demo mode for documentation.
+
+Generates SVG snapshots of every screen and sub-mode including overlays.
+All data comes from DemoDevice and DemoCraftClient — no hardware or
+network required.
+
+Usage:
+    cd tui && uv run python scripts/take_screenshots.py
+"""
 
 import asyncio
 
 from birdcage_tui.app import BirdcageApp
-
-SCREENS = {
-    "f1": "dashboard",
-    "f2": "control",
-    "f3": "signal",
-    "f4": "system",
-}
+from birdcage_tui.screens.control import ControlScreen
+from birdcage_tui.widgets.craft_panel import CraftPanel
 
 OUT_DIR = "/home/rpm/claude/ham/satellite/winegard-travler/site/public/screenshots"
 
 
-async def main():
-    for key, name in SCREENS.items():
+async def _screenshot_basic_tabs():
+    """F1 Dashboard, F2 Control (manual), F3 Signal, F4 System."""
+    tabs = {
+        "f1": "dashboard",
+        "f2": "control",
+        "f3": "signal",
+        "f4": "system",
+    }
+    for key, name in tabs.items():
         app = BirdcageApp()
         app.demo_mode = True
 
@@ -23,7 +33,6 @@ async def main():
             await pilot.pause()
             await pilot.press(key)
             await pilot.pause()
-            # Let workers populate data.
             await asyncio.sleep(1.5)
 
             path = f"{OUT_DIR}/tui-{name}.svg"
@@ -31,4 +40,107 @@ async def main():
             print(f"Saved {path}")
 
 
+async def _screenshot_craft_search():
+    """F2 Control > Craft sub-mode with search results."""
+    app = BirdcageApp()
+    app.demo_mode = True
+
+    async with app.run_test(size=(120, 40)) as pilot:
+        await pilot.pause()
+        await pilot.press("f2")
+        await pilot.pause()
+
+        control = app.query_one("#control", ControlScreen)
+        control.switch_mode("craft")
+        await pilot.pause()
+
+        # Trigger a search — uses DemoCraftClient
+        panel = app.query_one("#ctrl-craft-panel", CraftPanel)
+        panel.post_message(CraftPanel.SearchRequested(""))
+        await asyncio.sleep(1.0)
+
+        path = f"{OUT_DIR}/tui-craft-search.svg"
+        app.save_screenshot(path)
+        print(f"Saved {path}")
+
+
+async def _screenshot_craft_tracking():
+    """F2 Control > Craft sub-mode actively tracking the Moon."""
+    app = BirdcageApp()
+    app.demo_mode = True
+
+    async with app.run_test(size=(120, 40)) as pilot:
+        await pilot.pause()
+        await pilot.press("f2")
+        await pilot.pause()
+
+        control = app.query_one("#control", ControlScreen)
+        control.switch_mode("craft")
+        await pilot.pause()
+
+        # Start tracking the Moon (always above horizon in demo)
+        panel = app.query_one("#ctrl-craft-panel", CraftPanel)
+        panel.post_message(
+            CraftPanel.TrackRequested(
+                target_type="celestial",
+                target_id="moon",
+                name="Moon",
+                min_el=5.0,
+            )
+        )
+        await asyncio.sleep(2.5)
+
+        path = f"{OUT_DIR}/tui-craft-tracking.svg"
+        app.save_screenshot(path)
+        print(f"Saved {path}")
+
+        control._stop_craft_tracking()
+        await pilot.pause()
+
+
+async def _screenshot_console():
+    """F5 Console overlay."""
+    app = BirdcageApp()
+    app.demo_mode = True
+
+    async with app.run_test(size=(120, 40)) as pilot:
+        await pilot.pause()
+        await asyncio.sleep(1.0)
+
+        await pilot.press("f5")
+        await pilot.pause()
+        await asyncio.sleep(0.5)
+
+        path = f"{OUT_DIR}/tui-console.svg"
+        app.save_screenshot(path)
+        print(f"Saved {path}")
+
+
+async def _screenshot_camera():
+    """F6 Camera overlay."""
+    app = BirdcageApp()
+    app.demo_mode = True
+
+    async with app.run_test(size=(120, 40)) as pilot:
+        await pilot.pause()
+        await asyncio.sleep(1.0)
+
+        await pilot.press("f6")
+        await pilot.pause()
+        await asyncio.sleep(0.5)
+
+        path = f"{OUT_DIR}/tui-camera.svg"
+        app.save_screenshot(path)
+        print(f"Saved {path}")
+
+
+async def main():
+    await _screenshot_basic_tabs()
+    await _screenshot_craft_search()
+    await _screenshot_craft_tracking()
+    await _screenshot_console()
+    await _screenshot_camera()
+    print(f"\nAll screenshots saved to {OUT_DIR}/")
+
+
 asyncio.run(main())