feat(tour): a welcome of its own, the owner's order, and the way to codes

The tour opens on a welcome over the dimmed Checklist, then shows the bar
along the top, then the Checklist and Timeline with their looks, Routines,
Archive and Settings. Codes get three steps that walk the way in (the game
in Settings, its Codes tab, the codes), and the last step points at Replay
the introduction. A replay now dims and locks the page like the first run,
keeping only Close tour. Subjects out of sight scroll into view, and the
ring stays inside the window.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/DESIGN.md

@@ -640,13 +640,21 @@ legend on the same baseline as "Next: …".
   get no marker.
 - **The tour (2026-10-18, owner).** Every reader takes it once before using the app: new readers
   straight after setup, returning readers on their first visit, and readers who saw the earlier tour
-  once more. Routines → Checklist → Pick a layout → Timeline → Redeem codes → Archive → Settings.
-  - It floats over the page it describes. While forced, the page behind is `inert`. It can be
-    scrolled and seen, but not clicked. There is no Skip, and a reload restarts at step 1.
+  once more. The order is the owner's (2026-10-18): a welcome on its own over the dimmed Checklist,
+  saying things have changed and a tour is starting, so the first highlight is not missed while the
+  reader is still reading → the bar along the top, for getting around → the Checklist with
+  Relaxed / Structured → the Timeline with New /
+  Classic → Routines → Archive → Settings → the way to codes in three steps (the game in Settings →
+  Your games, its Codes tab, the codes) → where to replay the tour (Settings → Appearance → Replay
+  the introduction).
+  - It floats over the page it describes. The page behind is `inert`: it can be scrolled and seen,
+    but not clicked. There is no Skip, and a reload restarts at step 1.
   - Each step rings what it is about (owner, 2026-10-18: greying the page "makes sense, but it should
-    highlight the option"): the nav tab for Routines, Checklist, Archive and Settings, the Checklist
-    or the Timeline board for the two comparing steps, the codes list for codes. While forced, the
-    rest of the page is dimmed around it. The ring is a fixed layer drawn over the target's box
+    highlight the option"): the nav tab for Routines, Archive and Settings, the Checklist or the
+    Timeline board for the two comparing steps, the game's row, its Codes tab and the codes list for
+    codes, and the Replay button. A subject out of sight is scrolled into view. The rest of the page
+    is dimmed around it and inert, in a replay from Settings too (owner, 2026-10-18); a replay differs
+    only in having Close tour. The ring is a fixed layer drawn over the target's box
     (`TourSpotlight`), not the target raised above a scrim, so no stacking context can trap it.
   - "Pick a layout" (on the Checklist) and the Timeline step each hold a two-way switch, Relaxed /
     Structured and New / Classic. The switch changes the page behind in place, and the selected one
@@ -659,4 +667,4 @@ legend on the same baseline as "Next: …".
   - Returning readers are moved to Relaxed as the tour opens. New readers keep the look they chose in
     setup.
   - Continue stays in a fixed place and Back sits beside it. Only a replay ("Replay the
-    introduction" in Appearance) has a way out, "Close tour", with no scrim.
+    introduction" in Appearance) has a way out, "Close tour".