feat(profile): add profile settings and LLM user context

docs/frontend-design-cookbook.md

@@ -45,6 +45,7 @@ Global neutrals are defined in `frontend/src/app.css` using CSS variables.
 - Products: `--accent-products`
 - Routines: `--accent-routines`
 - Skin: `--accent-skin`
+- Profile: `--accent-profile`
 - Health labs: `--accent-health-labs`
 - Health medications: `--accent-health-meds`
 
@@ -114,6 +115,7 @@ These classes are already in use and should be reused:
 - Filter toolbars for data-heavy routes should use `GET` forms with URL params so state is shareable and pagination links preserve active filters.
 - Use the products filter pattern as the shared baseline: compact search input, chip-style toggle rows (`editorial-filter-row` + small `Button` variants), and apply/reset actions aligned at the end of the toolbar.
 - For high-volume medical data lists, default the primary view to condensed/latest mode and offer full-history as an explicit secondary option.
+- For profile/settings forms, reuse shared primitives (`FormSectionCard`, `LabeledInputField`, `SimpleSelect`) before creating route-specific field wrappers.
 - In condensed/latest mode, group rows by collection date using lightweight section headers (`products-section-title`) to preserve report context without introducing heavy card nesting.
 - Change/highlight pills in dense tables should stay compact (`text-[10px]`), semantic (new/flag change/abnormal), and avoid overwhelming color blocks.
 - For lab results, keep ordering fixed to newest collection date (`collected_at DESC`) and remove non-essential controls (no lab filter and no manual sort selector).
@@ -192,6 +194,7 @@ These classes are already in use and should be reused:
   - `frontend/src/routes/+page.svelte`
   - `frontend/src/routes/products/+page.svelte`
   - `frontend/src/routes/routines/+page.svelte`
+  - `frontend/src/routes/profile/+page.svelte`
   - `frontend/src/routes/health/lab-results/+page.svelte`
   - `frontend/src/routes/skin/+page.svelte`
 - Primitive visuals: