Docs: Initial tutorial site scaffold with SDK tutorials, program layout, and interactive components

[DiegoCarpenter]

Adds a VitePress docs site to dropset-alpha following the pattern from dropset-beta and solana-stablecoin-registry.

Includes:

Main docs

• Introduction, core concepts, architecture overview
• Program structure — all 10 instructions documented
• On-chain accounts — market, seat, trader balance, PDAs
• Quickstart guide

SDK tutorials

• Connect to a market using toMarketViewAll
• Post an order end-to-end with toOrderInfoArgs
• Price utilities — atomsToUiAmount, uiPriceToAtomsPrice

Interactive components

• CU Cost Explorer — filterable table comparing Dropset competing protocols
• Order Book Visualizer — step-through diagram of how each instruction affects the order book
• Instruction Cards — expandable quick-reference for all 10 instructions

Infrastructure

• Makefile targets: make docs, make docs-build, make docs-prettier, make docs-prod
• GitHub Actions: build-docs, deploy, quick-lint, semantic-pr

Run locally with: make docs

[DiegoCarpenter]

Also I know this PR is huge, since it's the initial docs scaffold. But it's all additive — no existing files were modified, only new files added to docs/, .github/workflows/, cfg/, and the Makefile. I didn't touch anything in the main codebase. I'm happy to break it into smaller PRs if preferred — for example splitting CI/infrastructure from content pages from interactive components, etc. Let me know what works best for review.

[alnoki]

What is this for?

[DiegoCarpenter]

Oh shoot, this was a mistake. This was added accidentally — dropset-alpha got picked as a git submodule unintentionally during my initial commit. I'll remove it now.

[alnoki]

What is this for?