Problem: tbl_deep_extend merges user platforms on top of defaults, so
all four default platforms survive even when the user only configures a
subset. The picker then shows platforms the user never intended to use.
Solution: before the deep merge, prune any default platform not present
in the user's platforms table. This preserves per-platform default
filling (the user doesn't have to re-specify every field) while ensuring
only explicitly configured platforms appear.
Problem: when required dependencies (GNU time/timeout, Python env) are
missing, config.setup() throws a raw error() that surfaces as a Lua
traceback. On macOS without coreutils the message is also redundant
("GNU time not found: GNU time not found") and offers no install hint.
Solution: wrap config.setup() in pcall inside ensure_initialized(),
strip the Lua source-location prefix, and emit a vim.notify at ERROR
level. Add Darwin-specific install guidance to the GNU time/timeout
not-found messages. Pass capability reasons directly instead of
wrapping them in a redundant outer message.
Problem: the deprecated vim.g.cp_config fallback was kept for
backwards compatibility after the rename to vim.g.cp in v0.7.6.
Solution: drop the shim entirely and update the setup() deprecation
target to v0.7.7.
Problem: when opening a contest for the first time (metadata not
cached), the setup_code hook fired before state.set_language() was
called, causing state.get_language() to return nil inside the hook.
Solution: call state.set_language(lang) before the hook in the
provisional-buffer branch of setup_contest(). The value is already
computed at that point and is identical to what setup_problem() sets
later, so the early write is idempotent.
