feat(dirty-content-fingerprint): apiserver/xcecli meson pass fingerprint to go_build

Both apiserver/meson.build and xcecli/meson.build add
XCE_DIRTY_FINGERPRINT=get_option('dirty_fingerprint'), unquoted,
identically positioned to the existing XCE_GIT_COMMIT/XCE_BUILD_TIME
entries.

Verified independently by review with a distinct test value: fresh
configure + real ninja builds of both binaries confirm the value reaches
go build's actual invocation (visible in go version -m's recorded -ldflags
build setting), matches the C-side -DVERSION_DIRTY_FINGERPRINT= from the
same configure, and degrades to empty identically to the two pre-existing
vars when omitted.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/frontend/apiserver/meson.build

@@ -58,6 +58,7 @@ custom_target('apiserver',
             'BUILD_ROOT="@BUILD_ROOT@"',
             'XCE_GIT_COMMIT=' + get_option('commit_id'),
             'XCE_BUILD_TIME=' + get_option('build_time'),
+            'XCE_DIRTY_FINGERPRINT=' + get_option('dirty_fingerprint'),
             go_build_program,
             '@INPUT@', '@OUTPUT@'],
   env:     go_env,

src/frontend/xcecli/meson.build

@@ -14,6 +14,7 @@ custom_target('xcecli',
             'BUILD_ROOT="@BUILD_ROOT@"',
             'XCE_GIT_COMMIT=' + get_option('commit_id'),
             'XCE_BUILD_TIME=' + get_option('build_time'),
+            'XCE_DIRTY_FINGERPRINT=' + get_option('dirty_fingerprint'),
             go_build_program,
             '@INPUT@', '@OUTPUT@'],
   env:     go_env,