Time formatting and server test fixes land

Locale-aware week/date formatting added (8c82f9e)

Std.Time now supports configurable locales and locale symbols for date/time formatting, including first-day-of-week-aware week calculations. This also adds week-based year support (Y) and threads the week-start parameter through weekOfYear/alignedWeekOfMonth, which matters for TR35-style formatting and non-Monday locales.

Server interactive waitFor now fails fast on worker death (7a6c59a)

The test runner’s waitForMessage helper now aborts promptly if the language server reports a fatalError, instead of hanging until an outer timeout. That makes waitFor-based interactive tests more reliable and gives a direct error when a file worker crashes or header processing fails fatally.

TZDB lookup now prefers TZ/TZDIR over /etc/localtime (ea73a5b)

Time zone resolution was reworked so missing /etc/localtime no longer breaks lookups when TZ or TZDIR are available. The search logic now re-reads TZDIR on each lookup and handles TZ parsing explicitly, fixing an environment-sensitive failure in zone rule discovery.

dupNamespace moved into the general linter framework (c04a83a)

The duplicate-namespace check was upstreamed from the env-linter path into Lean.Linter, with new dedicated implementation code and updated test wiring. This is mostly a refactor, but it makes the linter available in the broader text-linter framework and aligns Lean’s built-in linting structure with mathlib.

Other misc changes

• Removed the low-value worker_crash server-interactive test, then reintroduced it as part of the waitForMessage regression coverage.
• Test harness cleanup: full .lake directories are now wiped in pkg tests to avoid stale config reuse.