fix(lower): route remaining bare-name sites through resolver + close 0102 [0102d]

Final 0102 sub-step. fix-0102c landed resolveBareCallee and routed the
primary call path + parameter target typing through it, leaving four other
bare-name consumer sites on the old first-wins path. Route the SAME resolver
through all four, gated exactly as the call path (plain top-level identifier,
no scope-mangle / UFCS alias / local shadow; act on .func / .ambiguous, fall
through on .none so single-author / local / std / qualified / foreign-single
resolution is byte-for-byte unchanged):

1. Default-argument expansion (expandCallDefaults): omitted trailing args
   fill from the RESOLVED author's defaults, not the winner's.
2. Function-value conversion (closure(fn) and the bare-fn-as-value func_ref /
   fn-ptr / closure-coercion path): captures the resolved author's FuncId.
3. Free-function UFCS (recv.fn() -> fn(recv, ...)): dispatches the resolved
   author for the receiver's source.
4. Comptime #run of a bare call: lowerMainAndComptime now sets
   current_source_file per decl, so a `NAME :: #run f()` in an imported
   module resolves f from THAT module's flat imports (own-author wins) instead
   of the main file's perspective (which made it spuriously ambiguous).

Regression tests: examples/0730-0734 (default-arg, closure+fn-value, UFCS,
comptime #run, UFCS-ambiguity), each fails on pre-fix code and passes after.
issues/0102-flat-import-same-signature-collision.md written RESOLVED with the
4-sub-step root cause and regression-test paths.

examples/expected/0730-modules-flat-same-name-default-arg.exit

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

examples/expected/0730-modules-flat-same-name-default-arg.stderr

@@ -0,0 +1 @@
+

examples/expected/0730-modules-flat-same-name-default-arg.stdout

@@ -0,0 +1,2 @@
+from_a binds a.cfg default (10): ok
+from_b binds b.cfg default (20): ok

examples/expected/0731-modules-flat-same-name-closure.exit

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

examples/expected/0731-modules-flat-same-name-closure.stderr

@@ -0,0 +1 @@
+

examples/expected/0731-modules-flat-same-name-closure.stdout

@@ -0,0 +1,4 @@
+from_a closure binds a.pick (1): ok
+from_b closure binds b.pick (2): ok
+from_a fn-value binds a.pick (1): ok
+from_b fn-value binds b.pick (2): ok

examples/expected/0732-modules-flat-same-name-ufcs.exit

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

examples/expected/0732-modules-flat-same-name-ufcs.stderr

@@ -0,0 +1 @@
+

examples/expected/0732-modules-flat-same-name-ufcs.stdout

@@ -0,0 +1,2 @@
+from_a v.bump() binds a.bump (+1): ok
+from_b v.bump() binds b.bump (+100): ok

examples/expected/0733-modules-flat-same-name-comptime-run.exit

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

examples/expected/0733-modules-flat-same-name-comptime-run.stderr

@@ -0,0 +1 @@
+

examples/expected/0733-modules-flat-same-name-comptime-run.stdout

@@ -0,0 +1,2 @@
+a.sx #run binds a.compute (7): ok
+b.sx #run binds b.compute (70): ok

examples/expected/0734-modules-flat-same-name-ufcs-ambiguous.exit

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

examples/expected/0734-modules-flat-same-name-ufcs-ambiguous.stderr

@@ -0,0 +1,5 @@
+error: 'dup' is ambiguous; declared by multiple imported modules — qualify the call
+  --> examples/0734-modules-flat-same-name-ufcs-ambiguous.sx:14:19
+   |
+14 |     print("{}\n", v.dup());
+   |                   ^^^^^

examples/expected/0734-modules-flat-same-name-ufcs-ambiguous.stdout

@@ -0,0 +1 @@
+