Add Done button, tablet controls, super admin management, midnight strike reset, and activity log improvements

- Done button snaps block to full duration, marks complete, logs "Marked Done by User"; Reset after Done fully un-completes the block
- Session action buttons stretch full-width and double height for tablet tapping
- Super admin: reset password, disable/enable accounts, delete user (with cascade), last active date per user's timezone
- Disabled account login returns specific error message instead of generic invalid credentials
- Users can change own password from Admin → Settings
- Strikes reset automatically at midnight in user's configured timezone (lazy reset on page load)
- Break timer state fully restored when navigating away and back to dashboard
- Timer no longer auto-starts on navigation if it wasn't running before
- Implicit pause guard: no duplicate pause events when switching already-paused blocks or starting a break
- Block selection events removed from activity log; all event types have human-readable labels
- House emoji favicon via inline SVG data URI
- README updated to reflect all changes

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

backend/app/routers/sessions.py

@@ -14,6 +14,7 @@ from app.models.subject import Subject  # noqa: F401 — needed for selectinload
 from app.models.session import DailySession, TimerEvent
 from app.models.user import User
 from app.schemas.session import DailySessionOut, SessionStart, TimerAction
+from sqlalchemy import delete as sql_delete
 from app.utils.timer import compute_block_elapsed, compute_break_elapsed
 from app.websocket.manager import manager
 
@@ -194,12 +195,15 @@ async def timer_action(
 
         # When break starts, implicitly pause the main block timer so elapsed
         # time is captured accurately in the activity log and on page reload.
+        # Only write the pause if the block is actually running.
         if body.event_type == "break_start" and block_id:
-            db.add(TimerEvent(
-                session_id=session.id,
-                block_id=block_id,
-                event_type="pause",
-            ))
+            _, already_paused = await compute_block_elapsed(db, session.id, block_id)
+            if not already_paused:
+                db.add(TimerEvent(
+                    session_id=session.id,
+                    block_id=block_id,
+                    event_type="pause",
+                ))
 
         db.add(TimerEvent(
             session_id=session.id,
@@ -235,32 +239,48 @@ async def timer_action(
     if body.event_type in ("start", "select", "reset") and body.block_id is not None:
         prev_block_id = session.current_block_id
         if prev_block_id and prev_block_id != body.block_id:
-            db.add(TimerEvent(
-                session_id=session.id,
-                block_id=prev_block_id,
-                event_type="pause",
-            ))
-            # Autoflush means the implicit pause above is visible to the helper.
-            prev_block_elapsed_seconds, _ = await compute_block_elapsed(
+            prev_block_elapsed_seconds, prev_already_paused = await compute_block_elapsed(
                 db, session.id, prev_block_id
             )
+            # Only write an implicit pause if the previous block was actually running.
+            if not prev_already_paused:
+                db.add(TimerEvent(
+                    session_id=session.id,
+                    block_id=prev_block_id,
+                    event_type="pause",
+                ))
+                # Recompute elapsed now that the pause event is included.
+                prev_block_elapsed_seconds, _ = await compute_block_elapsed(
+                    db, session.id, prev_block_id
+                )
 
     # Update current block if provided
     if body.block_id is not None:
         session.current_block_id = body.block_id
 
-    # Record the timer event
+    # Record the timer event (select events are not persisted — they only drive WS broadcasts)
     event = TimerEvent(
         session_id=session.id,
         block_id=body.block_id or session.current_block_id,
         event_type=body.event_type,
     )
-    db.add(event)
+    if body.event_type != "select":
+        db.add(event)
 
     # Mark session complete if event is session-level complete
     if body.event_type == "complete" and body.block_id is None:
         session.is_active = False
 
+    # Reset removes completed status — delete any complete events for this block
+    if body.event_type == "reset" and event.block_id:
+        await db.execute(
+            sql_delete(TimerEvent).where(
+                TimerEvent.session_id == session.id,
+                TimerEvent.block_id == event.block_id,
+                TimerEvent.event_type == "complete",
+            )
+        )
+
     await db.commit()
     await db.refresh(session)
 
@@ -283,6 +303,7 @@ async def timer_action(
         "block_elapsed_seconds": block_elapsed_seconds,
         "prev_block_id": prev_block_id,
         "prev_block_elapsed_seconds": prev_block_elapsed_seconds,
+        "uncomplete_block_id": event.block_id if body.event_type == "reset" else None,
     }
     await manager.broadcast(session.child_id, ws_payload)