Add narrative text and a day-significance rank to the interpreter

Each of the day's top significant transits now gets a short sentence
describing what it classically means and which area of life its house
governs, condensed from Sepharial's Transits and Planetary Periods
(1920, public domain) plus a small table of traditional house
significations. The day-level line also shows its rank out of the 4
defined levels, e.g. "Notable (2/4)". Docs (CLAUDE.md, README,
docs/input-output-format.md, docs/reading.md) updated to match,
including a full worked example in docs/reading.md.

CLAUDE.md

@@ -71,7 +71,10 @@ deck_in_a_dash/
   res/                          Tarot card art (22 RWS Major Arcana JPEGs),
                                  Waite's "Pictorial Key to the Tarot" (PDF,
                                  public domain — source of all card/spread
-                                 text), logo, research notes.
+                                 text), Sepharial's "Transits and Planetary
+                                 Periods" (PDF, public domain — source of
+                                 interpreter/src/narrative.c's text), logo,
+                                 research notes.
   engine/
     third_party/astronomy/      Vendored cosinekitty/astronomy C library
                                  (MIT, pinned commit — see VENDORED.md).
@@ -199,11 +202,14 @@ into the Pebble watchapp unchanged later. Only `reading_print_text`/
 
 A second, separate top-level module and **its own binary**
 (`dist/interpreter-cli`, sibling to `dist/deck-engine`) that scores *how
-significant a day's transits are* — the first piece of a larger "turn the
-raw reading into an actual narrative" effort described in project chat
-history, not yet producing any narrative text. `deck-engine` itself is
-deliberately unchanged by this beyond gaining `--format json`; the two
-binaries compose over that JSON, never by linking together:
+significant a day's transits are* and, for each of the top items, prints
+a short narrative sentence about what that transit classically means —
+the first piece of a larger "turn the raw reading into an actual
+narrative" effort described in project chat history; the Celtic Cross
+spread itself isn't woven into that narrative yet (see
+`docs/reading.md`). `deck-engine` itself is deliberately unchanged by
+this beyond gaining `--format json`; the two binaries compose over that
+JSON, never by linking together:
 
 ```bash
 make          # -> dist/deck-engine (unchanged; --format json is new) and dist/interpreter-cli
@@ -223,11 +229,15 @@ between the two binaries (see the next bullet).
   every aspect in `reading->transits.aspects[]`, keeps the **top 5** by
   score in `DailyInterpretation.top_items[]` (descending, evicting the
   rest), and classifies the day into a `DaySignificance` enum (`DAY_QUIET`
-  ... `DAY_MAJOR`) from the single highest-scoring item.
-  `interpretation_deserves_framing()` is true only at `DAY_MAJOR` — the
-  intended hook for giving the Celtic Cross reading a "this matters"
-  intro sentence naming `top_items[0]` on days that earn it; that
-  rendering doesn't exist yet, `main.c`'s report is plain text only.
+  ... `DAY_MAJOR`) from the single highest-scoring item. The enum also
+  carries a trailing `DAY_SIGNIFICANCE_COUNT` sentinel (not a real level)
+  purely so callers can print the level as a rank, e.g. `main.c`'s
+  `"%s (%d/%d)"` → `"Notable (2/4)"` — `interp.day_level + 1` out of
+  `DAY_SIGNIFICANCE_COUNT`. `interpretation_deserves_framing()` is true
+  only at `DAY_MAJOR` — the intended hook for giving the Celtic Cross
+  reading a "this matters" intro sentence naming `top_items[0]` on days
+  that earn it; that rendering doesn't exist yet, `main.c`'s report is
+  plain text only.
 - Score = `transiting-planet weight (slow/outer planets score higher) ×
   orb tightness (1.0 = exact, ~0 = at the edge) × natal-luminary bonus
   (transits to natal Sun/Moon score higher than to other planets)`. The
@@ -235,6 +245,29 @@ between the two binaries (see the next bullet).
   thresholds in `significance.c` are hand-tuned, not derived from
   anything physical — expect to retune them once real readings are
   compared against how "major" a day actually feels.
+- **`narrative.c`/`narrative.h`** supplies `main.c`'s one-sentence
+  description printed under each top item, condensed from Sepharial's
+  *Transits and Planetary Periods* (1920, public domain —
+  `res/Transits_and_Planetary_Periods.pdf`), Chapter VIII "Effects of
+  Transits". Per transiting planet it holds a `base` description plus a
+  `harmonious`/`discordant` addendum, shown only under a trine/sextile or
+  square/opposition respectively (either may be `""` if the source gives
+  none); a conjunction is treated as neutral — base only — since
+  Sepharial's own text says a conjunction "takes the nature of what it
+  conjoins," which isn't modelled here. The Moon and Pluto aren't in that
+  chapter (fast lunar transits were out of scope for a year-ahead
+  forecasting book; Pluto wasn't discovered until 1930) — their text is
+  original, written for this project, not drawn from Sepharial. Each
+  narrative is also framed by *where* it's happening: `narrative_print()`
+  takes the transiting planet's whole-sign house (1-12, relative to the
+  natal chart, same as everywhere else in this codebase) and prefixes an
+  "In matters of ..." line naming that house's traditional area of life,
+  from a small `k_house_area[12]` table of standard whole-sign house
+  significations — centuries-old convention, not attributed to any single
+  source (same status as the sign/aspect names already in `astro.c`).
+  Passing a house outside 1-12 (the same "no data" sentinel `reading_io.c`
+  uses elsewhere) omits that framing and prints the planet's narrative on
+  its own.
 - **`reading_print_json`** (`engine/src/reading.c`) is the wire format:
   the full `DailyReading` (natal, transits, spread), using the
   language-independent `astro_*_slug()`/`tarot_*_slug()` accessors
@@ -261,10 +294,11 @@ between the two binaries (see the next bullet).
   it before printing sign/house), since that's supplementary display
   context rather than something scoring depends on.
 - **Deliberately header-only dependency on the engine, throughout**:
-  `significance.h`/`reading_io.h` `#include engine/src/reading.h` for the
-  struct/enum *definitions*, but the root `Makefile` never compiles or
-  links any engine `.c` file (or the vendored Astronomy Engine) into the
-  interpreter's binary or tests — every
+  `significance.h`/`reading_io.h`/`narrative.h` `#include` engine headers
+  (`reading.h`/`astro.h`) for the struct/enum *definitions*, but the root
+  `Makefile` never compiles or links any engine `.c` file (or the
+  vendored Astronomy Engine) into the interpreter's binary or tests —
+  every
   test in `interpreter/tests/` runs against hand-built JSON text or
   hand-built `DailyReading` values, with no real ephemeris/tarot-draw
   call involved anywhere. Consequently `reading_io.c` (planet/aspect/sign
@@ -287,3 +321,7 @@ between the two binaries (see the next bullet).
 - `engine/i18n/de.lang`'s card/spread text is an original translation of
   that same public-domain English text, made for this project — not
   taken from any specific published German edition.
+- Transit narrative text in `interpreter/src/narrative.c`: condensed from
+  Sepharial's *Transits and Planetary Periods* (1920, public domain —
+  `res/Transits_and_Planetary_Periods.pdf`), except the Moon and Pluto
+  entries, which are original (see narrative.c's own comment for why).