[plainprogrammer]

Closes #326

Spec 074 (spec, v0.6.1; verification). Factory data, placeholder card images; all phone shots are a 360px viewport in the narrow frame, light and dark.

What changed

1. A row menu opened near the bottom of a phone is no longer behind the tab bar (every Menu, fixed once in the component). Below 640px, on a page with a tab bar, opening a menu scrolls the page just far enough that the list ends 8px above the bar (the controller's reveal; scroll-margin-top/-bottom on .c-menu__list). An empty ::after room box under the open list lets the page scroll that far at its end (a prototype showed the last rows need it); a list taller than the room starts under the app bar. Nothing moves when the list is already clear, at 640px and wider, or with no tab bar; instant scroll under prefers-reduced-motion. A menu is closed before Turbo caches the page, so Back restores with every menu closed (AC-1.13).
2. The missing tab bar in spec 071's shots 04 and 05 was the frame, not the page. A narrow frame taller than the window's viewport is clipped and loses the fixed bar (an 815px frame in a 1280x800 window reproduces the picture exactly). Recorded in the screenshots workflow note; a guard example keeps the bar on the fourteen deck-family pages. No page change.
3. The DeckPage previews match the page. DeckPage.html and DeckPagePhone.html drew "Move copies" on 12 rows each that have no proxy; they now draw the empty menu cell the page builds. menu_cell in the design-system fixture too.
4. Found while doing 3, ruled in by the coordinator under the maintainer's delegation (Option 1): the real deck page misaligned its zones' columns at phone width (menu column 46px in a zone with proxies, 16px in one without, so Cost and Total sat 30px apart): spec 068's empty cell had broken spec 060 AC-3.11, hidden by a fixture that drew a menu on every row. The zone tables' menu column now has a floor of 4rem (64px, the wide layout's own width) below 640px of the container. Restores 060's rule; no criterion of 060 or 068 changes.

Owed to the maintainer

• The floor's cost (ruled, recorded in the spec's Decision 6): the Card column is 18px narrower in a zone with a row menu (48px in a zone with none) at a fine pointer. Only the pathological worst case, a 60-character name with no space, six pips and 1,234 proxies, is affected visibly: its table spills 19px past its container (1px before at a fine pointer, about 13px at a coarse one); the page never scrolls sideways and realistic rows fit. Wrapping the unbroken proxy tag in the zone tables would remove the spill; it is a ProxyTag ruling, listed under Out of Scope.
• components.css:127 still says the menu controller adds "arrow keys" (it never did); it is the design export's file, left alone; Menu.md corrects the claim and says so, so the next export fixes it.
• Headless Firefox has a fine pointer, so the coarse-pointer sizes (44px rows, the coarse trigger) are not shown or measured here; the committed AC-1.15 example injects every coarse rule.

Verification

• New spec/system/menu_tab_bar_clearance_spec.rb: 29 examples, written first; the red run is in verification.md (menus 50 to 137px behind the bar, margins 0px, list top 465 vs 65, menu column 16px vs 64px, the Back case restoring an open menu). Eight hand mutation checks each fail the example that guards them. After merging main: the file with design_system_files_spec, design_system_deck_components_spec and select_touch_floor_spec, 99 examples, 0 failures. The wider neighbours (deck page, proxies, shape panel, the examples that open menus in a narrow frame): 144 and 45 examples, 0 failures. RuboCop, YARD and Brakeman clean; the full bin/ci ran at the push (see the CI run below).
• Spec reviewed twice (Opus, read-only), plan twice, the 0.6.0 change once, implementation review (Mode B): SPEC-ALIGNED WITH MINOR FINDINGS, all taken.

Screenshots (360px viewport; "before" is emulated by switching the new margins, room box and scroll off, not built from main)

Menu opened with its trigger 40px above the bar. Before (the last three items are behind the bar) and after (all four items end 8px above it):

before, light	after, light	after, dark

The last row of the page with proxies of two finishes (eight items), before and after (dark):

before, dark	after, dark

The zones' columns (Main with a proxy row, Sideboard with an owned card), before and after (light):

before	after

The worst case after the floor (its table spills 19px; the page does not scroll sideways) and the phone preview (dark):

worst case, after	phone preview, dark

The workflow, a menu opening near the bottom (the first frames after the click show the list behind the bar before the page scrolls it clear):

All 24 images and the GIF: docs/specs/074-deck-pages-phone-width/screenshots/ (also the card page's and the collection table's menus, the deck page at 1280px with a menu open, unchanged, and the desktop preview), listed in verification.md.

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