fix(ir): resolve named-const array dims (0083) + materialize literal slice args (0084)

Two silent-miscompile codegen fixes:

0083 — named-const array dimension. `TypeResolver.resolveCompound`'s array
arm resolved the dimension with `if int_literal ... else 0`, so a named const
(`N :: 16; [N]T`) hit the silent `else 0`: the array became 0-length / 0-byte
and element access ran out of bounds (garbage for scalars, bus error for
slice/pointer/struct elements). The arm now delegates the dimension to
`inner.resolveArrayLen` (symmetric with `inner.resolveInner` for the element).
The stateful `Lowering.resolveArrayLen` evaluates it as a compile-time integer
across the comptime-constant / generic-value / module-global const tables and
emits a diagnostic — no fabricated length — when it isn't one.

0084 — `.[...]` literal passed directly as a call arg. `lowerArrayLiteral`
always yields an aggregate array value; the array→slice conversion is the
caller's job. The local-bound var-decl path did it, but the call-arg coercion
path had no array→slice arm, so `classify([N]T, []T)` returned `.none` and the
raw array was passed where a slice was expected (callee read its {ptr,len}
header off the wrong bytes → 0 / garbage / segfault). `classify` now returns a
new `.array_to_slice` plan for same-element `[N]T → []T`, and `coerceToType`
emits the existing `array_to_slice` op — identical to the local-bound path.

Regressions (fail-before/pass-after demonstrated on the pre-fix compiler):
  examples/0140-types-named-const-array-dim.sx (s64 + string + struct elems)
  examples/0141-types-slice-literal-direct-call-arg.sx (string + []s64)

Gate: zig build, zig build test, bash tests/run_examples.sh (387 passed).
Issues 0083 and 0084 marked RESOLVED.

examples/expected/0140-types-named-const-array-dim.exit

@@ -0,0 +1 @@
+0

examples/expected/0140-types-named-const-array-dim.stderr

@@ -0,0 +1 @@
+

examples/expected/0140-types-named-const-array-dim.stdout

@@ -0,0 +1,3 @@
+scalar a0=7 a3=42
+string s0=hi s1=yo
+struct p0x=1 p0y=2 p2x=5

examples/expected/0141-types-slice-literal-direct-call-arg.exit

@@ -0,0 +1 @@
+0

examples/expected/0141-types-slice-literal-direct-call-arg.stderr

@@ -0,0 +1 @@
+

examples/expected/0141-types-slice-literal-direct-call-arg.stdout

@@ -0,0 +1,4 @@
+str direct=2
+str local=2
+num direct=100
+num local=100