chore: restore v fmt compliance on master

[metif12]

Problem

master fails the CI formatting gate on all three platforms, so no other CI step
runs at all:

build (ubuntu-latest):   X Check formatting
build (macos-latest):    X Check formatting
build (windows-latest):  X Check formatting

v fmt -verify vls/ reports 17 of the 24 .v files as unformatted:

call_hierarchy.v  compilation_test.v  diagnostics_scheduler.v  document_highlight.v
folding_range.v   handlers.v          handlers_test.v          index.v
index_test.v      integration_test.v  interop.v                interop_test.v
lsp.v             lsp_test.v          main.v                   run_command.v
semantic_tokens.v
Encountered a total of: 17 formatting errors.

See run 35838854684.

Cause

Formatting drifted as features landed — mostly struct field alignment going stale
when a field or trailing comment was added, plus a handful of call sites that no
longer fit on one line:

 struct LSPDiagnostic {
 	message  string
 	severity int
 	source   ?string @[json: 'source'] // diagnostic source identifier, e.g. 'vlang'
-	code     ?string @[json: 'code'] // optional diagnostic code, e.g. 'unused_variable'
-	tags     ?[]int @[json: 'tags'] // 1 = unnecessary, 2 = deprecated
+	code     ?string @[json: 'code']   // optional diagnostic code, e.g. 'unused_variable'
+	tags     ?[]int  @[json: 'tags']   // 1 = unnecessary, 2 = deprecated

The gate only runs on master and pull requests, so this is invisible until the
formatting step is reached.

Fix

Run v fmt -w . and commit the result. 1273 insertions, 1259 deletions across the
17 files. No semantic change: git diff -w reduces to 46 insertions / 32
deletions, all of it line reflow, e.g.

 fn build_v_line_info_args_multifile(rel_file string, line_info string) []string {
-	return ['-w', '-check', '-nocolor', '-vls-mode', '-line-info', '${rel_file}:${line_info}', '.']
+	return ['-w', '-check', '-nocolor', '-vls-mode', '-line-info', '${rel_file}:${line_info}',
+		'.']
 }

Formatter version

Produced with V 0137eb5 — the same vlang/v revision CI builds from, so this
does not introduce formatter-version churn. Verified with the same compiler:

v fmt -verify .   ->  exit 0

Validation

V 0137eb5, Windows.

• v . builds clean.
• compilation_test.v, interop_test.v, lsp_test.v: 3 passed, 3 total.
  These are the files that compile on master today.

index_test.v and handlers_test.v are excluded because they currently fail to
compile on master; that is fixed separately in
#526, and this branch is independent of
it.

[metif12]

Consolidated rather than merged on its own.

handlers_test.v does not compile on master, so no branch that leaves that broken can
have a green CI run, and this change is what fixes it. Keeping it separate would have meant
every other PR stayed red.

Folded into #535, along with the v fmt compliance work, the handshake path escaping fix, the
dup2 outside assert fix, and a new fix for resolving vlib through a compiler wrapper
script that this change exposed.

Please review #535 instead. Nothing here is lost.

[metif12]

Closed in favour of #535: v fmt compliance folded into #535 (green-build restoration).