fix: increase heatmap cell sizes for readability

Activity calendar: 13px → 16px cells (+20%).
Hour-of-week grid: 14px → 21px cells (+50%), gap 2→3px.

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

Author: wesm

frontend/src/lib/components/analytics/Heatmap.svelte

@@ -1,10 +1,10 @@
 <script lang="ts">
   import { analytics } from "../../stores/analytics.svelte.js";
 
-  const CELL_SIZE = 13;
+  const CELL_SIZE = 16;
   const CELL_GAP = 2;
   const CELL_STEP = CELL_SIZE + CELL_GAP;
-  const LABEL_WIDTH = 32;
+  const LABEL_WIDTH = 36;
   const HEADER_HEIGHT = 16;
   const DAY_LABELS = ["", "Mon", "", "Wed", "", "Fri", ""];
 

frontend/src/lib/components/analytics/HourOfWeekHeatmap.svelte

@@ -1,11 +1,11 @@
 <script lang="ts">
   import { analytics } from "../../stores/analytics.svelte.js";
 
-  const CELL_SIZE = 14;
-  const CELL_GAP = 2;
+  const CELL_SIZE = 21;
+  const CELL_GAP = 3;
   const CELL_STEP = CELL_SIZE + CELL_GAP;
-  const ROW_LABEL_WIDTH = 32;
-  const COL_LABEL_HEIGHT = 18;
+  const ROW_LABEL_WIDTH = 36;
+  const COL_LABEL_HEIGHT = 22;
   const DAY_LABELS = [
     "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun",
   ];