Extract pages into lib/page/ modules; thin down bbs.rb

Each page is now a self-contained module with a configure(tui) class
method. Shared helpers live in TUIHelpers. bbs.rb is reduced to
constants, chrome, and wiring.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/page/helpers.rb

@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+
+module TUIHelpers
+  def tc(style, str)   = "#{THEME.fetch(style, THEME[:normal])}#{str}#{THEME[:reset]}"
+  def cont_w           = term_cols - CONT_X - 1
+  def cont_h           = term_rows - 4
+
+  def fmt_date(iso)
+    Time.parse(iso.to_s).strftime('%Y-%m-%d')
+  rescue
+    iso.to_s
+  end
+
+  def wordwrap(text, width)
+    words = text.to_s
+                .gsub(/\[([^\]]+)\]\([^)]+\)/, '\1')
+                .gsub(/[#*_`~>|\\]/, '')
+                .gsub(/\r?\n+/, ' ')
+                .strip
+                .split
+    lines, line = [], +''
+    words.each do |w|
+      if    line.empty?                         then line << w
+      elsif line.length + 1 + w.length <= width then line << ' ' << w
+      else  lines << line.dup; line = +w
+      end
+    end
+    lines << line unless line.empty?
+    lines
+  end
+
+  def wiki_list_render
+    list_h  = cont_h - 3
+    visible = @items[@scroll, list_h] || []
+    if visible.empty?
+      text 'No items found.', x: CONT_X, y: CONT_Y, style: THEME[:normal]
+    else
+      list visible.map { |p| p.title[0, cont_w - 2] },
+           x: CONT_X, y: CONT_Y,
+           selected: @item_sel - @scroll,
+           style: THEME[:normal], highlight: THEME[:selected]
+      if (page = @items[@item_sel])
+        hint = page.description.to_s.strip[0, cont_w]
+        text hint, x: CONT_X, y: CONT_Y + cont_h - 2, style: THEME[:normal] unless hint.empty?
+      end
+    end
+    text '↑↓ navigate  Enter read  q back', x: CONT_X, y: CONT_Y + cont_h, style: THEME[:normal]
+  end
+
+  def open_wiki_page(back:)
+    return unless (page = @items[@item_sel])
+    @detail     = wordwrap(WIKI.content(page.id), cont_w)
+    @page_title = page.title
+    @page_meta  = "#{fmt_date(page.created_at)}  #{WIKI.page_url(page.locale, page.path)}"
+    @prev_page  = back
+    @scroll     = 0
+    go :page_view
+  end
+end