Fix segfault: add mutex for ANSI terminal operations

Problem: Intermittent segfaults when running `bild --time 0 **/*` with
many concurrent builds. Core dumps showed crashes in libncursesw's
free() function during terminal cleanup.

Root cause: ANSI.getTerminalSize and other ANSI terminal library
calls are not thread-safe. With mapConcurrentlyBounded running up to
8 analyses concurrently, multiple threads were calling ANSI functions
simultaneously, causing memory corruption in the ncurses library.

Solution: Add global MVar terminalLock to serialize all ANSI terminal
operations. Wrap all ANSI function calls (cursor movement, line
clearing, etc.) with withMVar terminalLock.

Changes: - Add terminalLock :: MVar () in Omni/Log/Concurrent.hs -
Wrap all ANSI calls in withMVar terminalLock:
  - initializeLines: cursor column, clear line - updateLine: cursor
  up/down, column set, clear line - updateLineState: cursor up/down,
  column set, clear line - withLineManager: cursor up

Tested: 5 consecutive runs of `bild --time 0 **/*` complete without
segfaults (previously failed 1-2 out of 3 runs).

0 files changed, 0 insertions, 0 deletions