term: move the term core to subprojects/term

The core now builds, tests, and benchmarks alone, as a Meson subproject
with no dependency on the main tree.

- include/term/ holds term.h and the header-only unicode/. src/ holds
  the core and its private headers. The main tree gets only
  include/term through term_dep, so it cannot reach a private header.
- The term tests, the term benchmarks, the Kitty parser suite, and
  tools/amalgamate.py and tools/generate_unicode.py move with it. The
  tests run as term:<name>.
- The main build passes its -march (arch_flag) and b_ndebug to the
  subproject. A directory configured before this commit needs
  meson configure -Dterm:arch_flag=-march=... once.
- The term tests compile with -UNDEBUG. They do work inside assert.
- The subproject exports term_test_dep with term_api.h, for the main
  tree's render, thumbnail, color, and selection tests.
- The Kitty bridge used struct vector2i and has not compiled since the
  public API redesign. It builds again. 2 of its 14 tests fail: REP
  after a tab, and a cursor report after a resize.
- dirgraph.py drops the term and unicode layers. Its self-test uses pty.
- The symbols test ignores the __odr_asan symbols that ASan adds.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 32 insertions, 0 deletions

diff --git a/include/term/term_types.h b/include/term/term_types.h
new file mode 100644
index 0000000..78be371
--- /dev/null
+++ b/include/term/term_types.h
@@ -0,0 +1,32 @@
+#ifndef TERM_TYPES_H
+#define TERM_TYPES_H
+
+/* Marks the public functions. The library builds with hidden symbols, so
+ * only these are visible outside a shared build. A host can define it
+ * first, for example as __declspec(dllimport). */
+#ifndef TERM_API
+#if defined(__GNUC__) || defined(__clang__)
+#define TERM_API __attribute__((visibility("default")))
+#else
+#define TERM_API
+#endif
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct term_vector2i {
+    int x, y;
+};
+
+struct term_span {
+    int begin;
+    int end;
+};
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif