fix+feat: layer cards, ocean floor, notifications, units, log, photos

Layer picker:
- Fix blank cards: app:layout_columnWeight → android:layout_columnWeight
  (GridLayout children require android: namespace for weight attributes)
- Add Distance unit chips (nm/km/mi) to UNITS section

Map layers:
- Fix ocean floor: use addLayerAbove(lastFillLayer) instead of addLayerAt(0)
  so base rasters appear above OFM water/land fills but below roads+labels
- CardView elevation 16dp→4dp to eliminate visible shadow border

Notifications:
- Add POST_NOTIFICATIONS to manifest
- Request it alongside location permissions on Android 13+ (TIRAMISU+)

Conditions sheet:
- showOverlay() now always hides bottom sheet (STATE_HIDDEN) so it can't
  leak onto non-map pages; bottom padding (80dp) added to Safety+Log panes

Log entries:
- Log entry form visible always (was only shown while recording)
- Photo-only events filtered from track timeline; photos appear only when
  paired with real text in a log entry

Anchor watch:
- Inputs and output radius now use configured depth unit (ft/m)
  with label updates and ft→m conversion before calculation

Photos:
- Tap thumbnail in track event log → fullscreen dialog viewer

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

3 files changed, 56 insertions, 0 deletions

diff --git a/android-app/app/src/main/assets/docs/getting_started.md b/android-app/app/src/main/assets/docs/getting_started.md
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+# Getting Started with Nav
+
+Welcome to your sailing companion. Nav is designed to provide you with all the essential information you need while on the water.
+
+## Navigation Bar
+Use the navigation bar at the bottom to switch between:
+- **Map:** View your current position, AIS targets, and tidal currents.
+- **Instruments:** View detailed performance data like wind, speed, and depth.
+- **Log:** Access your trip log and record voice entries.
+- **Safety:** Quick access to MOB and Anchor Watch.
+
+## Instrument Panel
+The instrument panel can be expanded from the bottom of the map. 
+- **Swipe up** to see more details.
+- **Swipe down** to minimize it and see more of the map.
+
+## Help & Documentation
+You can find more detailed information by tapping the "Help" icon in any of the main screens.
diff --git a/android-app/app/src/main/assets/docs/instruments.md b/android-app/app/src/main/assets/docs/instruments.md
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+# Sailing Instruments
+
+The instrument panel provides real-time data from your sensors and boat polars.
+
+## Wind Data
+- **AWS (Apparent Wind Speed):** The wind speed felt by the boat.
+- **TWS (True Wind Speed):** The actual wind speed across the water.
+- **TWD (True Wind Direction):** The compass direction the wind is blowing from.
+
+## Boat Performance
+- **BSP (Boat Speed):** Speed through the water (from your speedo).
+- **SOG (Speed Over Ground):** Actual speed relative to the earth (from GPS).
+- **VMG (Velocity Made Good):** Speed directly upwind or downwind.
+- **Polar %:** Your current speed relative to the theoretical maximum for your boat.
+
+## Navigation
+- **HDG (Heading):** The direction the bow is pointing.
+- **COG (Course Over Ground):** The actual path the boat is tracking (includes leeway and current).
+- **Depth:** Current depth below the keel.
diff --git a/android-app/app/src/main/assets/docs/safety.md b/android-app/app/src/main/assets/docs/safety.md
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+# Safety First
+
+Nav includes critical safety features that work offline.
+
+## MOB (Man Overboard)
+The **MOB button** is always accessible in the Safety tab.
+1. Tap the large **MOB** button immediately if someone falls overboard.
+2. The app will record the current position and start a timer.
+3. A large arrow will show the bearing and distance back to the MOB point.
+4. An audible alarm will sound continuously.
+5. Tap **RECOVERED** only once the person is safely back on board.
+
+## Anchor Watch
+Monitor your boat's movement while at anchor.
+1. Tap the **Anchor** icon in the Safety tab.
+2. Configure your watch circle radius based on your scope.
+3. Tap **SET ANCHOR** to start monitoring.
+4. If your boat moves outside the circle, a high-priority alarm will sound.
+5. The alarm works in the background even if the screen is off.