feat(build): register deepslate shared-base contract (#77)

[BharathASL]

Description

Registers block/deepslate.svg as a second shared-base master in tools/base-sync.json, so deepslate-variant ores are drift-checked against it the same way stone-variant ores are checked against block/stone.svg. The marker group is deepslate_base and the shared sections are defs and group:deepslate_base. derivatives starts empty because no deepslate ore has been authored yet; each one is added to that list as it lands.

textures/block/deepslate.svg now carries the contract surface: the slate base fill, the crevice drop shadows and the strata plates sit inside <g id="deepslate_base">, a root <defs> block is present for parity with the stone master, and the file carries the shared-base header. The rasterized deepslate.png is byte-identical to main (SHA-256 5441591454358407d003ce9678cb6215a4b357497cc51e5dc1fcdfd35dd8cfa1 before and after), and the tiling audit reports zero seam discontinuity.

tools/test/base-sync.test.mjs covers the new registry entry, the shipped master's compliance, and a deepslate derivative harness against mock SVGs: drift in the strata plates, the crevice shadows and the base fill is detected, and an unlisted SVG carrying <g id="deepslate_base"> is rejected.

CONTRIBUTING.md §3 "Ore & Material Consistency" now documents the deepslate base alongside the stone base, including which sections derivatives must copy and which derivatives list a new ore goes in.

Refs #77. This delivers the "Strict base deepslate contract established for all deepslate ores" criterion; the bedrock strata and cobbled deepslate criteria remain open.

Affected Assets

• textures/block/deepslate.svg
• tools/base-sync.json
• tools/test/base-sync.test.mjs
• CONTRIBUTING.md

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Type of Change

• feat: New vector texture master, blockstate, or compiler capability
• fix: Tiling fix, palette correction, or bugfix
• docs: Documentation improvement
• chore / refactor: Maintenance, dependencies, or codebase cleanup

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Contributor Checklist

Vector Texture Standards (if adding/modifying SVGs)

• Authored as a clean $512\times512$ SVG (viewBox="0 0 512 512").
• Primary shapes are aligned to the $32\text{px}$ texel grid ($16\times16$ grid). Strata plates are on the grid; the crevice drop shadows are offset 8px down by design and are unchanged from main.
• Seamless Toroidal Tiling: Checked and verified that elements wrapping across $X$ and $Y$ edges align perfectly without seams or chopped shapes.
• Ore Consistency: Not applicable; no ore texture is added. The deepslate master is the base future deepslate ores must match.
• Free of leftover AI generation comments, unnecessary editor namespaces, or embedded raster images.

Build & Verification

• Ran npm run build locally and verified that the pack compiles successfully.
• Verified textures in-game or inspected the rasterized PNG outputs in dist/.

Git Hygiene & Standards

• Commit message(s) follow Conventional Commits (e.g., feat(textures): ...).
• Every commit is signed off with the Developer Certificate of Origin (git commit -s).
• Branch is rebased cleanly onto latest main with no merge commits.
• Formatting complies with .editorconfig (2-space indent, LF endings, trailing newline).

[ninja6-agent]

Blockers

• 4caf321 (commit message): The body is a single unwrapped 497-character line restating the diff, which breaches N6-COMMIT-05 (body optional, a line or two, wrapped at 72). The repo squashes with COMMIT_MESSAGES, so this lands on main verbatim. Cut the body to one or two lines wrapped at 72 (or drop it) and keep the detail in the PR description.

Nits

• PR title / 4caf321 subject: "deepslate and strata shared-base contracts" names two contracts, but only one is registered (block/deepslate.svg → deepslate_base; strata_plates is a subgroup inside it). Retitle to e.g. feat(build): register deepslate shared-base contract (#77).
• PR body: No reference to #77, whose acceptance criterion "Strict base deepslate contract established for all deepslate ores" this PR delivers, and the repo PR template (Affected Assets, checklist) is not used. Add Refs #77 (not Closes, since the bedrock/cobbled deepslate criteria are still open) and fill the template.
• textures/block/deepslate.svg:L24, textures/block/deepslate.svg:L70: Whitespace-only lines with trailing spaces, against .editorconfig trim_trailing_whitespace = true. Make them empty.
• CONTRIBUTING.md:L132-L153: The "Ore & Material Consistency" section still describes the shared-base contract as stone-only (stone_base, stone.svg). Add that deepslate-variant ores derive from textures/block/deepslate.svg and must copy <defs> and <g id="deepslate_base">, and must be added to that entry's derivatives list.

[ninja6-agent]

Blockers

None.

Nits

• textures/block/deepslate.svg:L9: "<defs> (if any)" contradicts the registry. sharedSections lists defs, and checkBaseSync fails a derivative with no <defs> ("missing the shared section "), so an ore author who takes "if any" at its word fails the build. Drop "(if any)"; derivatives must copy the (currently empty) <defs> block too.
• tools/base-sync.json:L9-L12: The stone entry's sharedSections is reflowed from one line to four with no content change. This is churn in an entry the PR does not otherwise touch. Restore ["defs", "group:stone_base"] and use the same one-line form for the deepslate entry at L21-L24.
• tools/base-sync.json:L19: The deepslate description leaves out the rule the stone entry states: anything shared must sit inside a listed sharedSections entry, or nothing compares it. Add that sentence so both base entries give the same guidance.