Add tm_server with SQLite, Svelte UI, and task-master TUI sync.

Introduces the web backend (auth, RBAC, project tokens, revisions),
YouTrack-or-taskmaster backend choice in the TUI, and a first-pass
embedded Svelte UI. The frontend is functional but needs a major rework.

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/syncbackend/youtrack_list.go

@@ -0,0 +1,29 @@
+package syncbackend
+
+import (
+	"context"
+
+	"task/internal/youtrack"
+)
+
+// ListYouTrackProjects lists projects via a master/instance token.
+func ListYouTrackProjects(ctx context.Context, baseURL, token string) ([]RemoteProject, error) {
+	client := &youtrack.Client{BaseURL: baseURL, Token: token}
+	projects, err := client.ListProjects(ctx)
+	if err != nil {
+		return nil, err
+	}
+	out := make([]RemoteProject, 0, len(projects))
+	for _, p := range projects {
+		name := p.Name
+		if name == "" {
+			name = p.ShortName
+		}
+		out = append(out, RemoteProject{
+			Key:  p.ShortName,
+			Name: name,
+			ID:   p.ID,
+		})
+	}
+	return out, nil
+}