fix(pipeline): release db_path/db_dir on the manifest abort paths; free the test harness cross arena

Second LSan round from the Linux leg, both verified green in the container
(532 passed, 0 failed under LSan):

- dump_and_persist_hashes' two semantic-manifest abort returns leaked BOTH of
  the function's strdups (db_path and db_dir, the latter otherwise freed only
  further down). Same ownership rule as the previous fix: every exit releases
  what the function allocated.

- test_parallel's sequential harness drives the passes directly and never
  destroyed ctx->seq_cross_arena, which the cross pass fills with the shared
  per-language registries (stdlib registrations included -- ~20MB per test).
  Production's run_sequential_pipeline destroys it after all passes; the
  harness now does the same.

Signed-off-by: Martin Vogel <martin.vogel.tech@gmail.com>

src/pipeline/pipeline.c

@@ -1734,12 +1734,19 @@ static int dump_and_persist_hashes(cbm_pipeline_t *p, const cbm_file_hash_t *bas
     if (cbm_pipeline_build_fresh_semantic_manifest(p->project_name, p->repo_path, p->mode,
                                                    &manifest, &manifest_count) != 0) {
         cbm_log_error("pipeline.err", "phase", "semantic_manifest");
+        /* db_path and db_dir are this function's strdups; the success tail and
+         * the publish-failure return release them, and these two aborts must
+         * too -- LSan caught exactly these paths leaking both strings. */
+        free(db_dir);
+        free(db_path);
         return CBM_PIPELINE_ABORT_PRESERVE_DB;
     }
     if (!cbm_pipeline_semantic_manifests_equal(baseline_manifest, baseline_count, manifest,
                                                manifest_count)) {
         cbm_log_warn("pipeline.abort", "reason", "semantic_inputs_changed");
         cbm_pipeline_free_semantic_manifest(manifest, manifest_count);
+        free(db_dir);
+        free(db_path);
         return CBM_PIPELINE_ABORT_PRESERVE_DB;
     }
 

tests/test_parallel.c

@@ -244,6 +244,15 @@ static cbm_gbuf_t *run_sequential_with_lsp_cross_and_mutator(
     }
     free(cache);
     cbm_registry_free(reg);
+    /* The cross pass builds its shared registries in the caller-owned
+     * ctx->seq_cross_arena precisely so they outlive pass_calls; production's
+     * run_sequential_pipeline destroys that arena after all passes, and this
+     * harness must too -- LSan flagged the whole registry arena (stdlib
+     * registrations included) leaking per test. */
+    if (ctx.seq_cross_arena_live) {
+        cbm_arena_destroy(&ctx.seq_cross_arena);
+        ctx.seq_cross_arena_live = false;
+    }
     return gbuf;
 }