tasks: shared task board with sticker rewards, difficulty levels, and calendar

Complete household task management system behind task_users auth group:
- Task CRUD with recurring schedules, assignees, tags, and optional difficulty
- Blobcat SVG sticker rewards on completion, rarity weighted by difficulty
- Sticker collection page with calendar view and progress tracking
- Redesigned cards with left accent urgency strip, assignee PFP, round check button
- Weekday-based due date labels for tasks within 7 days
- Tasks link added to homepage LinksGrid

CLAUDE.md

@@ -17,6 +17,14 @@ After calling the list-sections tool, you MUST analyze the returned documentatio
 Analyzes Svelte code and returns issues and suggestions.
 You MUST use this tool whenever writing Svelte code before sending it to the user. Keep calling it until no issues or suggestions are returned.
 
+## Common Svelte 5 Pitfalls
+
+### `{@const}` placement
+`{@const}` can ONLY be the immediate child of `{#snippet}`, `{#if}`, `{:else if}`, `{:else}`, `{#each}`, `{:then}`, `{:catch}`, `<svelte:fragment>`, `<svelte:boundary>` or `<Component>`. It CANNOT be used directly inside regular HTML elements like `<div>`, `<header>`, etc. Use `$derived` in the `<script>` block instead.
+
+### Event modifiers removed
+Svelte 5 removed event modifiers like `on:click|preventDefault`. Use inline handlers instead: `onclick={e => { e.preventDefault(); handler(); }}`.
+
 ### 4. playground-link
 
 Generates a Svelte Playground link with the provided code.