Add crop icons to resource tokens in Feudalism

[SorraTheOrc]

Summary

Replace the plain coloured token chips in Feudalism with tokens that display both a colour code AND a crop icon representing each resource type. Currently tokens are solid-colour circles — after this change each token should show a recognisable icon for its crop while retaining its distinct colour for quick visual identification.

User Story

As a player of Feudalism, I want the resource tokens to show crop icons (not just colours) so that I can identify resources by both colour and imagery, making the game more thematic and accessible.

Context

This work item depends on the crop material rename (CG-0MM5KBHTD0Y5Q5JV) being completed first, since the crop types and their colour mappings will be defined there.

Scope

Token Design

Each token should display:

1. A colour-coded background (circle/chip) matching the crop's assigned colour
2. A crop icon rendered on top of the background — either as a sprite/texture asset or as a simple programmatic drawing

Crop Icons Needed

Based on the crop mapping from CG-0MM5KBHTD0Y5Q5JV (subject to final choices made there):

Crop	Icon Concept
Oats	Grain sheaf / oat stalk
Flax	Flax flower / linen bundle
Barley	Barley ear
Turnip	Turnip root
Wheat	Wheat sheaf
Honey (wild)	Honeycomb / bee

Areas to update

• Token rendering in the Feudalism scene (market tokens, player token displays, token selection UI)
• Token assets: either create/source simple icon sprites (CC0/permissive license) or draw them programmatically with Phaser graphics
• Noble tile resource requirement indicators (if they show token-style icons)
• Card cost indicators (if they show token-style icons)
• Asset attribution in public/assets/CREDITS.md if new image assets are added

Acceptance Criteria

1. Each crop resource token displays a visible icon representing its crop type
2. Tokens retain their distinct colour coding for quick identification
3. Icons are visible and legible at the token sizes used in the game (market, player area, card costs)
4. If sprite assets are used, they are CC0 or permissive-licensed and attributed in CREDITS.md
5. Token icons appear consistently everywhere tokens are displayed (market, player area, card costs, noble requirements)
6. npm test passes
7. npm run build succeeds