bootstrap: meson build, test harness, CI, conventions, README/AGENTS (et0)

Phase 0 (task et0): lays the build/test/CI/convention groundwork before any
feature code.

- meson.build: project ggaze C11 -Wall -Wextra; deps gtk4/glib/gio/libadwaita;
  feature options gegl/jxl/avif/heif (auto); generated ggaze-config.h with
  app id, version, GGAZE_HAVE_* feature flags.
- tests: GLib g_test harness with separate unit/integration suites
  (--suite unit / --suite integration); test_bootstrap sanity test proves
  the harness compiles and the config header is reachable; -Db_coverage=true
  coverage target wired.
- CI: .woodpecker/ci.yml three lanes (minimal, gegl, asan) with xvfb for the
  integration track and a coverage lane that warns until M10.
- conventions: .clang-format (3-space, 80-col, K&R, *-on-var, return type on
  its own line) + .editorconfig matching docs/coding-conventions.md; CI
  clang-format --dry-run -Werror gate.
- top-level README.md (humans) and AGENTS.md (agents) pointing into docs/.
- LICENSE (GPL-3.0-or-later), .gitignore, dir placeholders.

Acceptance: meson setup build && ninja -C build && meson test -C build green;
clang-format --dry-run --Werror clean.

1 files changed, 15 insertions, 0 deletions

diff --git a/ggaze-config.h.in b/ggaze-config.h.in
new file mode 100644
index 0000000..c72677a
--- /dev/null
+++ b/ggaze-config.h.in
@@ -0,0 +1,15 @@
+#ifndef GGAZE_CONFIG_H
+#define GGAZE_CONFIG_H
+
+/* Generated by meson from ggaze-config.h.in — do not edit the build copy. */
+
+#define GGAZE_VERSION @GGAZE_VERSION@
+#define GGAZE_APP_ID  @GGAZE_APP_ID@
+
+/* Optional backends (1 = compiled in, 0 = absent). */
+#define GGAZE_HAVE_GEGL @GGAZE_HAVE_GEGL@
+#define GGAZE_HAVE_JXL  @GGAZE_HAVE_JXL@
+#define GGAZE_HAVE_AVIF @GGAZE_HAVE_AVIF@
+#define GGAZE_HAVE_HEIF @GGAZE_HAVE_HEIF@
+
+#endif /* GGAZE_CONFIG_H */
\ No newline at end of file