Render original survey signs with coherent browser atlas updates

The browser renderer at d5b3c26 draws geologist signs as small coloured rectangles, although the supplied pinned remake and public demo contain the actual sign images. This is visible on the original tutorial map after normal scouting and surveying.

Verified reference: paulwedeck/settlers-remake@6ad8c42. MapObjectDrawer selects objects file 1 sequences 94 coal, 95 gems, 96 gold, 97 iron, 98 sulfur, 99 empty. Each exists in the demo with two 14x24 frames and anchors (-8,-21). Twelve frames decoded to RGBA PNG successfully; original DAT SHA256 cf8d7a23b3188e6326b3e5918f135527de790ad38747b181b595e8dcfc11ad0a. Original rasters remain local pending redistribution evidence.

Acceptance:

• Import all twelve actual frames through the maintained converter, retaining source selectors, offsets, transparency and byte provenance. Require supported marker images during verification and startup.
• Derive visible marker identity and frame from the player's existing survey knowledge, including empty/exhausted results and expiry. Do not expose concealed deposits or other players' signs.
• Document the reference frame calculation honestly: original raw 0..15 values scale by 127/15, signs normalize against reference maximum 50, then choose the sequence frame. The game's current raw-count engineering representation is not a Gold runtime observation. Do not change mining reserves or rules as an incidental presentation fix.
• Keep atlas coordinates and image bytes coherent across browser updates. Emit an image addressed by its bytes, load the manifest-selected image and revalidate the small manifest. No cached old bitmap with new coordinates.
• Exercise public session/scene behavior, save/reload and expiry; compare converted atlas pixels with independently retained source-frame hashes; check actual browser output.
• Run lint, types, assets, production build, full unit/browser checks and exact-main CI. Verify original diagnostic artifact before closure.

Scope: browser original survey-symbol presentation and its asset delivery. This does not complete all graphics, original quantity balance, tutorial objectives, native presentation or Gold parity. Related broader issues #20, #39, #86 and #4 remain open.

Geologists now leave the original demo's survey signs, including empty results and both resource frames. The images retain their original pixels and anchors; expired signs disappear and save/reload preserves the player's discoveries. Mining quantities are unchanged.

All 349 unit tests and 385 browser checks pass, including the full rival battle. Implementation, validation details and passing CI. The retained CI reports also confirm all 385 steps without collected browser errors.