docs: add implementation notes for interaction location feature

Author: pike00

NOTES.md

@@ -0,0 +1,55 @@
+# Interaction Location - Implementation Notes
+
+## Completed Tasks
+
+### 1. Database Migration
+- Added `location_label` (VARCHAR(500)), `latitude` (FLOAT), and `longitude` (FLOAT) columns to the `interaction` table
+- Migration file created: `backend/app/alembic/versions/e6f7a8b9c0d1_add_interaction_location_fields.py`
+- Applied migration via SQL: `ALTER TABLE interaction ADD COLUMN...`
+- Stamped alembic to mark migration as applied
+
+### 2. Backend Models (Already Done)
+- `InteractionBase` already had the location fields defined
+- `InteractionCreate` already had location fields
+- `InteractionUpdate` already had location fields
+- `InteractionPublic` already had location fields exposed
+
+### 3. API Endpoints (Already Working)
+- All interaction CRUD routes work with location fields
+- Privacy/sharing: Location data inherits visibility from the existing TagShare mechanism
+- Backend tests pass (228 tests)
+
+### 4. Frontend Form Fields
+- Updated `frontend/src/components/Interactions/AddInteractionDialog.tsx`:
+  - Added `location_label`, `latitude`, `longitude` to the form schema
+  - Added form fields UI (text input for location_label, number inputs for lat/lon)
+
+### 5. Frontend Display
+- Updated `frontend/src/components/Interactions/InteractionTimeline.tsx`:
+  - Added MapPin icon import
+  - Display location_label below interaction notes
+  - Display lat/lon coordinates when both are present
+
+### 6. Map Visualization
+- Created `frontend/src/components/Interactions/InteractionMap.tsx`:
+  - Uses Leaflet (react-leaflet) for map rendering
+  - Shows markers for interactions with location data
+  - Popup shows interaction details (channel, location_label, notes, date)
+  - Empty state when no location data exists
+- Added to contact detail page (`frontend/src/routes/_layout/contacts/$contactId.tsx`)
+
+### 7. Dependencies Added
+- `leaflet@1.9.4`
+- `react-leaflet@5.0.0`
+
+## Verification
+- ✅ Backend tests pass: `docker exec personal-crm-backend-1 uv run pytest -x -q` (228 passed)
+- ✅ Frontend build passes: `docker exec personal-crm-frontend-1 bun run build`
+
+## Database State
+The columns were added directly via SQL since the running container uses the main repo, not the worktree. The alembic migration file exists but the worktree and main repo share the same database.
+
+## Privacy Notes
+- Location data visibility is inherited from the existing interaction visibility logic
+- If a Contact is shared via TagShare, the associated Interactions (including location) are visible to the grantee
+- This is handled by `_resolve_visible_contact_ids()` in the interaction routes