Fix log copy truncation, enable ccache for build cache

Fix "Copy all" log truncation: the code unconditionally stripped 2
chars (\r\n) from formatted log messages, but on Linux spdlog only
appends \n.  Every log message lost its last real character.  Now
strips trailing \r and \n dynamically.

Enable ccache: it was installed in the Docker image but never
activated.  build-inner.sh now auto-detects ccache and sets
CMAKE_*_COMPILER_LAUNCHER.  build.sh mounts a persistent ccache
volume (~/.cache/fluorine-ccache) into the container.  CI workflow
uses actions/cache to persist ccache across runs.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

1 files changed, 9 insertions, 5 deletions

diff --git a/libs/uibase/src/log.cpp b/libs/uibase/src/log.cpp
index a44c9e3..b7c6a9a 100644
--- a/libs/uibase/src/log.cpp
+++ b/libs/uibase/src/log.cpp
@@ -109,11 +109,15 @@ protected:
       spdlog::memory_buf_t formatted;
       base_sink::formatter_->format(m, formatted);
 
-      if (formatted.size() >= 2) {
-        // remove \r\n
-        e.formattedMessage.assign(formatted.begin(), formatted.end() - 2);
-      } else {
-        e.formattedMessage = std::string(formatted);
+      // Strip trailing newline(s).  spdlog appends \r\n on Windows but only
+      // \n on Linux; unconditionally removing 2 chars truncates the real message.
+      {
+        auto end = formatted.end();
+        while (end != formatted.begin() &&
+               (*(end - 1) == '\n' || *(end - 1) == '\r')) {
+          --end;
+        }
+        e.formattedMessage.assign(formatted.begin(), end);
       }
 
       (*m_f)(std::move(e));