Clear the clippy warnings, except the two that are not cosmetic

Down from 29 warnings to 2, in the spirit of 4ab95ff.

The doc warnings were all one mistake made repeatedly: a paragraph wrapped so
that a line *began* with `- ` or `+ `, which rustdoc reads as a markdown list
marker and the following lines as unindented continuations. The prose always
meant an em-dash. Fixed by moving the dash to the end of the previous line and
re-wrapping; not one word changed, which is the point - these comments record
things confirmed against real printers and are worth more than the warning.
The genuine lists just had their continuations de-indented and stayed lists.

The code ones are `match x { V(v) => .., _ => {} }` to `if let`, and nested
`if let Some(x) = .. { if cond { .. } }` to a let-chain. None had an `else`,
so each is the same control flow written once instead of twice.

Two warnings are left deliberately, because fixing them is not cosmetic:
`AmsTray` (544 bytes against 32) and `BambuReport` (984 against 120) both have
one variant far larger than the rest. The fix clippy wants is a `Box`, which
changes how every reader of those enums is written and puts an allocation on
the push_status path that currently has none. Worth measuring before doing,
not worth doing to silence a warning.

51 tests still pass.

src/printer/bambu_commands/mod.rs

@@ -7,9 +7,10 @@
 //! continuum-schemas for continuum.v1, which is a schema we designed
 //! ourselves and that both TS and Rust genuinely need.
 //!
-//! One file per Bambu *category* (`get_version.rs` for "info", `pushall.rs`
-//! + `print.rs` for "pushing"/"print" - see below for why those are two
-//! files, not one). Copy `get_version.rs`'s shape for your next command.
+//! One file per Bambu *category* (`get_version.rs` for "info",
+//! `pushall.rs` + `print.rs` for "pushing"/"print" - see below for why
+//! those are two files, not one). Copy `get_version.rs`'s shape for your
+//! next command.
 //!
 //! Mirrors continuum-schemas' `schemas/bambulab/` JSON Schemas - same
 //! category split, same "print vs pushing" correction (see that