Adds compiler/src/it/ (Maven-convention integration test directory) with
a Blaise-specific PDR driver. Four initial tests ported from the OPDF
integration suite: breakpoint+next, local variables, locals command,
and step-over. Test programs are adapted for Blaise (no FPC directives),
line numbers preserved to match the original commands files.
The pasbuild-integration-test plugin (phase: none) can be invoked as
'pasbuild integration-test'; it verifies pdr and the Blaise binary are
present, then delegates to compiler/src/it/run_tests.sh.
All four tests currently fail — line info in the OPDF section maps every
statement to the function-start address (per-stmt addresses require QBE
changes, tracked in future-improvements.adoc). The aspirational expected
files show exactly what each test should produce once OPDF is complete,
making failures a clear roadmap rather than noise.
Also adds PIE/ASLR support entry to future-improvements.adoc (Linux,
FreeBSD, macOS load-base strategies for the PDR debugger).