Parser would hang (infinite loop) when encountering newline tokens
inside certain constructs because expect() returns without advancing
position when the expected token doesn't match.
Fixed 5 places in parseBaseType, parsePrimaryPattern, parseTypeParams,
parseParamList, and parseUseDecl by adding newline-skipping at the
start of each iteration.
Verified: compiler no longer hangs/crashes on all 3 real-world apps
from apps/ (boko-framework, jwt-pitbul, nexus).
- examples/borrow.bux: working borrow expression example
- tests/borrow_test.nim: add 4 new tests for borrow & @[Shared]
- parser.nim: fix borrow parsing order (& before mut)
- Build verified: example compiles and runs