refactor(office): generalize DataTable layout and document TUI table skill

Unify project/user flex column layout into layoutFlexTable with per-subject
policy in model. Add office-tui-table skill and AGENTS notes; fix CI go mod
tidy drift and test matrix Go version to match go.mod 1.25.

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

cmd/office/model/table_layout.go

@@ -0,0 +1,20 @@
+package model
+
+// TableFlexLayout describes a list table where every column stays visible and
+// one flex column absorbs leftover pane width.
+type TableFlexLayout struct {
+	FlexColumnKey string
+	MinFlexWidth  int
+}
+
+// TableFlexLayoutFor returns a flex layout policy for subjects that show all columns.
+func TableFlexLayoutFor(subject Subject) (TableFlexLayout, bool) {
+	switch subject {
+	case SubjectProjects:
+		return TableFlexLayout{FlexColumnKey: "title", MinFlexWidth: 12}, true
+	case SubjectUsers:
+		return TableFlexLayout{FlexColumnKey: "email", MinFlexWidth: 16}, true
+	default:
+		return TableFlexLayout{}, false
+	}
+}