docs(finance/order-book): add walkthrough-script style guide

[mikemaccana]

Adds finance/order-book/docs/walkthrough-script-style.md — a style guide for narrating a Solana program's full lifecycle in tutorial/video scripts and README walkthroughs.

Why

Distilled from review feedback while editing the order-book tutorial script. Several conventions needed multiple rounds to land correctly; this captures them so the next walkthrough starts from the right defaults.

What it covers

• Per-handler account snapshots — one ADDED/UPDATED block per account, full fields shown, changes marked old -> new (no consolidating multiple accounts under one heading, no deltas-only blocks).
• on-curve vs off-curve labelling, verified against code — the gotchas that bit us: token vaults created via Anchor init + token::authority with no seeds are on-curve keypairs (only their authority is a PDA); large zero-copy accounts are client keypairs, not PDAs; ATAs are off-curve PDAs even though their owning wallet is on-curve.
• TOKEN MOVEMENT FROM/TO blocks wherever tokens move, annotated by kind (lock / fee sweep / payout / refund), and none on counter-only steps.
• Fee-accounting rules to state precisely (where generated, accrued vs swept, who pays, rounding direction, what generates no fee).
• Narrative conventions (protagonist first, bids highest-first, maker sets fill price, limit price stored on the order, partial vs full fill resting behaviour).
• Terminology — critbit is depth-bounded by key width, not "balanced"; bits zero-indexed from the right.

Note: this is currently a holding spot under the order-book example. It's intended for the quicknode/solana-claude-skill repo; happy to relocate or drop it from this repo if preferred.

Verification

Docs-only change; no code touched.

https://claude.ai/code/session_01G6iaAjzg8aoFwe8ZWWG9VR

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Generated by Claude Code

[mikemaccana]

Wrong repo, bot.