v0.1.11

lean-toolchain: worker bootstrap accepts lakefile.toml

build_lake_target_with_runner and its companion helpers
(target_declared_in_lakefile, package_name_from_lakefile) hardcoded
lakefile.lean, so any TOML-only Lake project failed worker bootstrap with
could not read .../lakefile.lean (No such file or directory). The bootstrap
path now picks the existing lakefile up front and dispatches declaration and
package-name checks on the file extension, so both lakefile.lean and
lakefile.toml projects bootstrap. TOML parsing consolidates onto the toml
crate via a new lean_toolchain::lakefile_toml module; the hand-rolled
state-machine TOML parser in modules.rs is gone.

lean-rs-worker-parent: Display now surfaces child stderr on fatal exits

impl Display for LeanWorkerError previously rendered
ChildExited / ChildPanicOrAbort as the exit status alone
("worker exited fatally with exit status: 1"). The captured child stderr on
LeanWorkerExit.diagnostics — populated by wait_with_stderr for exactly
this purpose since 0.1.10 — was unreachable through the Display surface,
forcing every downstream that logs tracing::error!("{err}") or stores
err.to_string() to pattern-match the variants and read the field by hand.

The Display rendering now appends the trimmed stderr tail when non-empty:

worker exited fatally with exit status: 1: could not dlopen X.dylib: image not found

Capped at 4 KiB so a runaway Lake / elan trace cannot blow up the formatted
string; the full text is still available on LeanWorkerExit.diagnostics. The
cut respects UTF-8 char boundaries and never lands inside an unterminated ANSI
CSI escape (Lake colourises its trace output). When diagnostics is empty,
the format collapses back to the original terse string.

No public-API change: the new helpers are private and the Display trait
signature is unchanged.