Introduces watch/, a real Pebble watchapp (built via pebble build) that

shows the daily tarot/astrology reading on-device: persistence, reading
computation, and UI screens, driven by the existing engine/interpreter
code linked in unchanged where possible.

Required engine-side changes to make that linking work:
- A compact low-precision ephemeris (lowprec_ephemeris.c) replacing the
  vendored ~127KB Astronomy Engine, which doesn't fit the watch's ~64KB
  app budget.
- Hand-rolled sqrt/atan2/sin/cos replacements for that ephemeris and
  astro.c's Ascendant calculation - Pebble's statically-linked libm
  hard-faults on real hardware under this app's -fPIE link for all four.
- narrative.c/guidance.c refactored from FILE*/fprintf onto snprintf-
  based buffers, since Pebble's SDK blocks fprintf at compile time.

interpreter/tests/narrative_test.c

@@ -9,115 +9,92 @@
 #include "../../engine/src/i18n.h"
 #include "../src/narrative.h"
 
-static const char *slurp(FILE *f) {
-  static char buf[4096];
-  long len = ftell(f);
-  rewind(f);
-  size_t n = fread(buf, 1, (size_t)len, f);
-  buf[n] = '\0';
-  return buf;
-}
-
 static void test_hard_aspect_shows_base_but_not_harmonious_bonus(void) {
   Aspect a = { .transiting_planet = PLANET_SATURN, .natal_planet = PLANET_MOON,
                .type = ASPECT_SQUARE, .orb = 1.0 };
-  FILE *f = tmpfile();
-  narrative_print(f, "  ", &a, 0);
-  const char *text = slurp(f);
+  char text[NARRATIVE_TEXT_MAX];
+  narrative_write(text, sizeof text, "  ", &a, 0);
 
   assert(strstr(text, "depression") != NULL);
   assert(strstr(text, "past associations") == NULL);
 
-  fclose(f);
   printf("PASS test_hard_aspect_shows_base_but_not_harmonious_bonus\n");
 }
 
 static void test_soft_aspect_adds_harmonious_bonus(void) {
   Aspect a = { .transiting_planet = PLANET_SATURN, .natal_planet = PLANET_SUN,
                .type = ASPECT_TRINE, .orb = 1.0 };
-  FILE *f = tmpfile();
-  narrative_print(f, "  ", &a, 0);
-  const char *text = slurp(f);
+  char text[NARRATIVE_TEXT_MAX];
+  narrative_write(text, sizeof text, "  ", &a, 0);
 
   assert(strstr(text, "depression") != NULL);
   assert(strstr(text, "past associations") != NULL);
 
-  fclose(f);
   printf("PASS test_soft_aspect_adds_harmonious_bonus\n");
 }
 
 static void test_conjunction_is_neutral_prints_base_only(void) {
   Aspect a = { .transiting_planet = PLANET_SATURN, .natal_planet = PLANET_SUN,
                .type = ASPECT_CONJUNCTION, .orb = 1.0 };
-  FILE *f = tmpfile();
-  narrative_print(f, "  ", &a, 0);
-  const char *text = slurp(f);
+  char text[NARRATIVE_TEXT_MAX];
+  narrative_write(text, sizeof text, "  ", &a, 0);
 
   assert(strstr(text, "depression") != NULL);
   assert(strstr(text, "past associations") == NULL);
 
-  fclose(f);
   printf("PASS test_conjunction_is_neutral_prints_base_only\n");
 }
 
 /* The Sun has no unconditional base text (see narrative.c) - a neutral
- * conjunction to it should print nothing at all. */
+ * conjunction to it should write nothing at all. */
 static void test_empty_base_and_neutral_aspect_prints_nothing(void) {
   Aspect a = { .transiting_planet = PLANET_SUN, .natal_planet = PLANET_MOON,
                .type = ASPECT_CONJUNCTION, .orb = 1.0 };
-  FILE *f = tmpfile();
-  narrative_print(f, "  ", &a, 0);
-  long len = ftell(f);
+  char text[NARRATIVE_TEXT_MAX];
+  narrative_write(text, sizeof text, "  ", &a, 0);
 
-  assert(len == 0);
+  assert(text[0] == '\0');
 
-  fclose(f);
   printf("PASS test_empty_base_and_neutral_aspect_prints_nothing\n");
 }
 
 static void test_discordant_aspect_on_empty_base_planet(void) {
   Aspect a = { .transiting_planet = PLANET_SUN, .natal_planet = PLANET_MOON,
                .type = ASPECT_OPPOSITION, .orb = 1.0 };
-  FILE *f = tmpfile();
-  narrative_print(f, "  ", &a, 0);
-  const char *text = slurp(f);
+  char text[NARRATIVE_TEXT_MAX];
+  narrative_write(text, sizeof text, "  ", &a, 0);
 
   assert(strstr(text, "Degradation") != NULL);
 
-  fclose(f);
   printf("PASS test_discordant_aspect_on_empty_base_planet\n");
 }
 
 static void test_known_house_adds_area_framing(void) {
   Aspect a = { .transiting_planet = PLANET_SATURN, .natal_planet = PLANET_MOON,
                .type = ASPECT_SQUARE, .orb = 1.0 };
-  FILE *f = tmpfile();
-  narrative_print(f, "  ", &a, 3);
-  const char *text = slurp(f);
+  char text[NARRATIVE_TEXT_MAX];
+  narrative_write(text, sizeof text, "  ", &a, 3);
 
   assert(strstr(text, "house 3") != NULL);
   assert(strstr(text, "communication") != NULL);
   assert(strstr(text, "depression") != NULL);
 
-  fclose(f);
   printf("PASS test_known_house_adds_area_framing\n");
 }
 
 static void test_unknown_house_omits_area_framing(void) {
   Aspect a = { .transiting_planet = PLANET_SATURN, .natal_planet = PLANET_MOON,
                .type = ASPECT_SQUARE, .orb = 1.0 };
-  FILE *f = tmpfile();
-  narrative_print(f, "  ", &a, 0); /* 0 = "no data" sentinel, not a real house */
-  const char *text = slurp(f);
+  char text[NARRATIVE_TEXT_MAX];
+  narrative_write(text, sizeof text, "  ", &a, 0); /* 0 = "no data" sentinel, not a real house */
 
   assert(strstr(text, "house") == NULL);
   assert(strstr(text, "depression") != NULL);
 
-  fclose(f);
   printf("PASS test_unknown_house_omits_area_framing\n");
 }
 
-/* Proves narrative_print() actually routes through i18n_get() rather
+/* Proves narrative_write() actually routes through i18n_get() rather
  * than just printing the hardcoded fallback - loads a translation file
  * that overrides one planet's base text and one house's area text, and
  * checks the override wins. Run last: i18n_load() replaces the
@@ -136,15 +113,13 @@ static void test_translation_catalog_overrides_fallback_text(void) {
 
   Aspect a = { .transiting_planet = PLANET_SATURN, .natal_planet = PLANET_MOON,
                .type = ASPECT_CONJUNCTION, .orb = 1.0 };
-  FILE *out = tmpfile();
-  narrative_print(out, "", &a, 3);
-  const char *text = slurp(out);
+  char text[NARRATIVE_TEXT_MAX];
+  narrative_write(text, sizeof text, "", &a, 3);
 
   assert(strstr(text, "UEBERSETZTER SATURN TEXT") != NULL);
   assert(strstr(text, "UEBERSETZTES HAUS DREI") != NULL);
   assert(strstr(text, "depression") == NULL); /* English fallback must not leak through */
 
-  fclose(out);
   printf("PASS test_translation_catalog_overrides_fallback_text\n");
 }