docs(mapgen-studio): add Pass 5 design-fixes spec (toolbar architecture v2, tile orientation, canvas affordances)

[mateicanavra]

This document establishes the fifth design pass on the mapgen studio redesign, covering five discrete changes.

X1 — Toolbar Architecture v2 restructures the top/bottom bar split into a clear Game vs World/Map zoning. The top bar becomes the Game toolbar, consolidating the saved-config selector, live Civ7 status, autoplay, Explore, save-deploy, retry/diagnostics, Run in Game, and an icon-only setup disclosure at the far right. The bottom bar becomes the World/Map console, holding studio status, History, Size, Players, Resources, Seed, reroll, auto-run, and Run. Last-run stats collapse into a History icon button with a hover tooltip. Resources moves to the bottom bar as a map setting, and the setup dropdown is scoped to pure Civ7 game setup (Leader, Civ, Difficulty, Speed). The History button doubles as copy-seed to preserve that affordance.

X2 — Grid Icon fixes a missing glyph in ViewControls.tsx where an empty <div> sits in place of the grid toggle icon, replacing it with the Grid3x3 lucide glyph. A categorical sweep confirmed no other empty icon placeholders exist in the codebase.

X3 — Tile Orientation corrects a 30° rotation bug where render.ts applies pointy-top polygon math to odd-Q (flat-top) hex layouts. The fix switches to flat-top vertex calculation for odd-Q tiles and verifies the associated center-spacing and bounds math. This pass also standardizes the tile-mesh contract across all visualizations: borders must be legible on any background, unfilled tiles render nothing, and the optional background grid follows a single consistent treatment.

X4 — White Flash on Refresh investigates a flash that survives the existing index.html dark-mode guard. The approach uses an earliest-inline-script sampler logging computed background colors and canvas presence into sessionStorage over the first ~1s of load, targeting three suspects: WebGL canvas white clear before first deck draw, an unstyled html element, or Vite injecting CSS via JS after first paint. The fix follows once the culprit is identified.

X5 — Pre-run Cursor suppresses the deck controller and grab cursor before a manifest exists, since panning pre-run moves nothing visible and reads as broken. Post-run behavior is unchanged.

[github-actions]

Railway preview (MapGen Studio): not provisioned for this PR.

Policy (Graphite stacks): previews are created only for the top-of-stack PR by default.

• To force a preview for this PR: add label railway-preview
• To suppress a preview: add label no-railway-preview

Debug: {"isClosed":false,"isFork":false,"suppress":false,"force":false,"isTopOfStack":false,"hasToken":true,"draft":false}

[mateicanavra]

Merge activity

• Jun 12, 8:50 PM UTC: A user started a stack merge that includes this pull request via Graphite.
• Jun 12, 9:53 PM UTC: Graphite rebased this pull request as part of a merge.
• Jun 12, 9:53 PM UTC: @mateicanavra merged this pull request with Graphite.