Fix the two remaining branch test failures (all green)

test/fx/test_type_mismatch.roc returned a bare quote literal `"hello"`,
which on this branch is an open literal reachable from main!'s signature.
It's generalized rather than defaulted, so the entry-point check reports
POLYMORPHIC VALUE (a load-bearing safety net — suppressing it makes the
checker accept the program and crash in postcheck) before the cross-module
platform-requirement check can report TYPE MISMATCH. Refactor the fixture
to return a concretely-typed Str (annotated local) so it genuinely
mismatches the platform's `() => {}`; the TYPE MISMATCH assertion is
unchanged.

Regenerate 3 drifted EXPECTED sections (--update-expected): a reordered
TYPE MISMATCH entry in fuzz_crash_019/020 and an improved mismatch region
(1:1:1:1 -> 4:6:4:13) in string_interpolation_type_mismatch. EXPECTED-only;
no report-text/body changes.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: jaredramirez

test/fx/test_type_mismatch.roc

@@ -1,5 +1,12 @@
 app [main!] { pf: platform "./platform/main.roc" }
 
+# The platform requires `main! : () => {}`, but this returns a Str.
+# The `msg : Str` annotation pins the body to a concrete Str so the mismatch
+# against the platform's required `{}` return surfaces as a TYPE MISMATCH.
+# (A bare `"hello"` would stay an open quote literal and the entry-point check
+# would instead report POLYMORPHIC VALUE — see fx_platform_test.)
 main! = || {
-    "hello"
+    msg : Str
+    msg = "hello"
+    msg
 }

test/snapshots/fuzz_crash/fuzz_crash_019.md

@@ -199,10 +199,10 @@ TOO FEW ARGS - fuzz_crash_019.md:84:2:86:3
 MISSING METHOD - fuzz_crash_019.md:86:11:86:17
 TYPE MISMATCH - fuzz_crash_019.md:98:4:104:3
 TYPE MISMATCH - fuzz_crash_019.md:105:2:105:54
+TYPE MISMATCH - fuzz_crash_019.md:77:11:77:14
 DECLARATION HAS NO VALUE - fuzz_crash_019.md:113:1:113:7
 DECLARATION HAS NO VALUE - fuzz_crash_019.md:116:1:116:13
 TYPE MISMATCH - fuzz_crash_019.md:119:2:119:10
-TYPE MISMATCH - fuzz_crash_019.md:77:11:77:14
 MISSING METHOD - fuzz_crash_019.md:105:55:105:66
 MISSING METHOD - fuzz_crash_019.md:105:55:105:72
 # PROBLEMS

test/snapshots/fuzz_crash/fuzz_crash_020.md

@@ -199,10 +199,10 @@ DECLARATION HAS NO VALUE - fuzz_crash_020.md:74:1:74:22
 MISSING METHOD - fuzz_crash_020.md:86:11:86:17
 TYPE MISMATCH - fuzz_crash_020.md:98:4:104:3
 TYPE MISMATCH - fuzz_crash_020.md:105:2:105:54
+TYPE MISMATCH - fuzz_crash_020.md:77:11:77:14
 DECLARATION HAS NO VALUE - fuzz_crash_020.md:113:1:113:7
 DECLARATION HAS NO VALUE - fuzz_crash_020.md:116:1:116:13
 TYPE MISMATCH - fuzz_crash_020.md:119:2:119:10
-TYPE MISMATCH - fuzz_crash_020.md:77:11:77:14
 MISSING METHOD - fuzz_crash_020.md:105:55:105:66
 MISSING METHOD - fuzz_crash_020.md:105:55:105:72
 # PROBLEMS

test/snapshots/string_interpolation_type_mismatch.md

@@ -11,7 +11,7 @@ x = 42
 y = "value: ${x}"
 ~~~
 # EXPECTED
-TYPE MISMATCH - string_interpolation_type_mismatch.md:1:1:1:1
+TYPE MISMATCH - string_interpolation_type_mismatch.md:4:6:4:13
 # PROBLEMS
 **TYPE MISMATCH**
 The `from_interpolation` method on `Str` has an incompatible type: