feat: phase 1 MVP — sections, services, drag-drop, renderers

Backend: migration 0002 (sections/items/urls/settings), CRUD +
fractional reorder, icon upload, settings, export/import, cached
status pings. Handler tests cover reorder, URL scheme validation,
settings round-trip.

Frontend: shared board store over the generated client, dnd-kit
layer (same-section, cross-section, section reorder persisted),
URL chooser popover, add/edit service dialog, settings dialog,
Bento + Cards renderers behind the shared seam, dark/light theme.

Generated with [Devin](https://devin.ai)

Authored By: TDvorak <[email protected]>
Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

apps/backend/internal/db/migrations/0002_board.sql

@@ -0,0 +1,36 @@
+-- +goose Up
+-- Board tree: sections > items > urls. position REAL = fractional ordering;
+-- a drag writes one row instead of renumbering the set.
+CREATE TABLE sections (
+    id         TEXT PRIMARY KEY,
+    name       TEXT NOT NULL,
+    position   REAL NOT NULL,
+    collapsed  INTEGER NOT NULL DEFAULT 0,
+    created_at TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ', 'now'))
+);
+
+CREATE TABLE items (
+    id         TEXT PRIMARY KEY,
+    section_id TEXT NOT NULL REFERENCES sections(id) ON DELETE CASCADE,
+    kind       TEXT NOT NULL DEFAULT 'service' CHECK (kind IN ('service', 'widget')),
+    name       TEXT NOT NULL,
+    icon       TEXT NOT NULL DEFAULT '',
+    position   REAL NOT NULL,
+    config     JSON,
+    created_at TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ', 'now'))
+);
+CREATE INDEX items_section_pos ON items(section_id, position);
+
+CREATE TABLE urls (
+    id       TEXT PRIMARY KEY,
+    item_id  TEXT NOT NULL REFERENCES items(id) ON DELETE CASCADE,
+    url      TEXT NOT NULL,
+    label    TEXT NOT NULL DEFAULT '',
+    position REAL NOT NULL
+);
+CREATE INDEX urls_item_pos ON urls(item_id, position);
+
+-- +goose Down
+DROP TABLE urls;
+DROP TABLE items;
+DROP TABLE sections;