docs: propagate unwrap-to-? migration into tutorial snippets

[memosr]

rust-client/src/bin/ uses the ? operator on build_consume_notes, but
three tutorial snippets still call .unwrap(). The migration reached the
large no_run listings, which CI compiles, but not the smaller
rust ignore snippets, which are never compiled and so drifted silently.

Three call sites, each now matching its source exactly:

• mint_consume_create_tutorial.md vs create_mint_consume_send.rs
• custom_note_how_to.md vs hash_preimage_note.rs
• unauthenticated_note_how_to.md vs unauthenticated_note_transfer.rs

The first one also resolves a contradiction inside its own file, which
already used ? in the final full listing further down.

Line wrapping differs between the three because the sources differ:
consume_request fits on one line, transaction_request does not. Each
snippet reproduces its own source rather than normalizing them.

Scope is limited to these three build_consume_notes call sites. No
repo-wide .unwrap() sweep was done, and other .unwrap() calls that
match their sources are untouched.

Docs-only change. cargo test --doc in docs/ passes (17 passed, 0 failed).
Ran prettier --write per CONTRIBUTING.md.