coverage: instrument the reanalyze library

The DUNE_INSTRUMENT_WITH change alone routed the reanalyze tests to an
instrumented rescript-tools, but the reanalyze library itself declared
no instrumentation backend, so its own 58 source files recorded zero
coverage (only the analysis/tools code it links was counted).

Add the (instrumentation (backend bisect_ppx)) stanza — matching every
other analysis/* and tools/* library — so analysis/reanalyze/src is
measured. Verified locally: reanalyze goes from 0 to ~61% line
coverage in the report.

The stanza is a no-op for normal builds (it only activates under
--instrument-with / DUNE_INSTRUMENT_WITH).

Author: JonoPrest

Makefile

@@ -303,8 +303,10 @@ coverage-lib: coverage-prepare
 # binary via `dune exec`, which would otherwise rebuild it *uninstrumented*.
 # Setting DUNE_INSTRUMENT_WITH=bisect_ppx (the env-var form of
 # `--instrument-with`) makes that `dune exec` match the config coverage-build
-# already used, so it runs the instrumented binary — no rebuild, no coverage
-# gap, and no de-instrumentation of the shared _build artifacts.
+# already used, so it runs the instrumented binary — no rebuild, no
+# de-instrumentation of the shared _build artifacts. (The reanalyze library
+# also carries its own bisect_ppx instrumentation stanza so its source is
+# counted, not just the analysis/tools code it links.)
 .PHONY: coverage-run
 coverage-run: coverage-lib
 	$(COVERAGE_TEST_ENV) node scripts/test.js -all

analysis/reanalyze/src/dune

@@ -1,5 +1,7 @@
 (library
  (name reanalyze)
+ (instrumentation
+  (backend bisect_ppx))
  (flags
   (-w "+6+26+27+32+33+39"))
  (libraries reactive yojson ml str unix))