core: #inst instant values + syntax-quote literal collapse (spec 2.3/2.4)

#inst (jolt-rnh): an instant is an immutable tagged struct
{:jolt/type :jolt/inst :ms <epoch-millis>} — equality and map-key hashing by
INSTANT, so different offsets denoting the same moment are =. The reader
parses RFC3339 with Clojure's partial-timestamp defaults (#inst "2020" is
2020-01-01T00:00:00.000Z) and errors on malformed input; inst?/inst-ms in
the overlay; pr-str prints the canonical
#inst "yyyy-MM-ddThh:mm:ss.fff-00:00" and round-trips; str gives the bare
RFC3339 string. Self-evaluating in the evaluator (like uuid/chars).

Syntax-quote (jolt-l2a): a syntax-quoted self-evaluating literal (string,
number, boolean, nil, keyword, char) collapses to the literal at READ time,
matching Clojure's reader — so nested/adjacent backticks over literals are
inert: (= "meow" ```"meow") is true (jank pass-adjacent). Symbols still
qualify and collections still template. General nested syntax-quote over
non-literals remains UNVERIFIED in spec S25.

Tests: inst-spec (18 cases incl. partial defaults, offsets, round-trip),
+10 literal-collapse reader rows, +5 conformance rows (321x3). Spec
02-reader S20/S25 updated to normative. Suite stable 4470/86.

docs/spec/02-reader.md

@@ -1,7 +1,7 @@
 # §2 The Reader (Lexical Syntax)
 
 **Status**: token grammar drafted; reader-macro catalog complete with
-normative entries; syntax-quote section carries two open divergences.
+normative entries; #inst and literal-collapse divergences resolved.
 Conformance: jolt `reader-forms-spec` + `reader-syntax-spec` (granularity
 model: jank's per-construct corpus, 62 files under
 `test/jank/{reader-macro,syntax-quote}` — adapted rows cited per entry).
@@ -150,9 +150,12 @@ false; `(NaN? ##NaN)` is true.
   read value. An unknown tag MUST be a read error (jank
   `fail-unsupported-tag`).
 - Built-in tags every implementation MUST provide: `#uuid "…"` → a UUID
-  value (§9 `parse-uuid` semantics — round-trips through printing), `#inst
-  "…"` → an instant (representation host-classified; ⚠ jolt currently reads
-  `#inst` as its bare string — divergence, filed).
+  value (§9 `parse-uuid` semantics — round-trips through printing), and
+  `#inst "…"` → an instant value: RFC3339 with partial-timestamp defaults
+  (`#inst "2020"` ≡ `#inst "2020-01-01T00:00:00.000-00:00"`), equality by
+  instant (offset-normalized), `inst?`/`inst-ms` (epoch milliseconds), printed
+  canonically as `#inst "yyyy-MM-ddThh:mm:ss.fff-00:00"` and round-tripping. A
+  malformed timestamp MUST be an error.
 
 **Conformance** (2.3): jolt `reader-forms-spec` "#() (% %N %&)" + new rows
 (symbolic values, stacked discard, conditionals); `uuid-spec` reader-literal
@@ -176,10 +179,11 @@ resolution:
   value; `~'sym` is the idiom for an intentionally-unqualified symbol.
 - S24. Syntax-quote distributes through collection literals (vectors, maps,
   sets) — qualification and unquoting apply inside them.
-- S25. Nested syntax-quotes expand recursively (quasiquote semantics); a
-  syntax-quoted self-evaluating literal is the literal: `(= "meow"
-  ```"meow")` is true. ⚠ jolt currently fails S25 (filed) — UNVERIFIED
-  pending the fix.
+- S25. A syntax-quoted self-evaluating literal is the literal, collapsed at
+  read time — so nested/adjacent backticks over literals are inert:
+  `(= "meow" ```"meow")` is true. General nested syntax-quote over symbols
+  and collections expands recursively (quasiquote semantics) — that general
+  case remains UNVERIFIED pending dedicated conformance rows.
 
 **Conformance**: jolt `reader-forms-spec` "syntax-quote" (gensym, unquote,
 splice) + conformance "syntax-quote fully-qualifies"; jank

docs/spec/coverage.md

@@ -7,8 +7,8 @@ community examples). jolt interns 550 of them.
 
 | Status | Count | Meaning |
 |---|---|---|
-| implemented+tested | 397 | in jolt and exercised by spec/conformance |
-| implemented-untested | 153 | in jolt, no direct test — spec entries will add them |
+| implemented+tested | 399 | in jolt and exercised by spec/conformance |
+| implemented-untested | 151 | in jolt, no direct test — spec entries will add them |
 | resolvable-not-interned | 22 | works in code but invisible to ns introspection (conformance finding) |
 | missing-portable | 19 | portable semantics, jolt lacks it — implementation gap |
 | special-form | 13 | specified in §3, not a library var |
@@ -345,9 +345,9 @@ UNVERIFIED field; that column will be added as entries land.
 | `indexed?` | implemented+tested | ✓ |
 | `infinite?` | implemented+tested | ✓ |
 | `init-proxy` | implemented-untested | ✓ |
-| `inst-ms` | implemented-untested | ✓ |
+| `inst-ms` | implemented+tested | ✓ |
 | `inst-ms*` | missing-portable |  |
-| `inst?` | implemented-untested | ✓ |
+| `inst?` | implemented+tested | ✓ |
 | `instance?` | implemented+tested | ✓ |
 | `int` | implemented+tested | ✓ |
 | `int-array` | implemented-untested | ✓ |