M1 step 3: Log writing and Storage Clean-up

- lib/storage_model (host-tested): FAT-safe names, daily Log paths,
  dates from Log/Capture file names, CleanupPlan by category and age,
  byte formatting
- StorageService does all card I/O on its task: queued Log lines are
  written in batches each second (dropped while Logs are paused),
  plus file listing and deletion jobs
- Settings > Storage moves into StoragePage: usage, Clean up
  (category, age with size preview, confirmation), Erase SD card
- Clock: local date for Log names
- Serial: log <text>, sd list

Verified on the device: lines land in /irc/dev/#test/2026-10-02.log
with folders created as needed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

lib/storage_model/src/storage_paths.h

@@ -0,0 +1,22 @@
+#pragma once
+
+#include <cstdint>
+#include <initializer_list>
+#include <string>
+
+namespace roro::storage {
+
+// Makes one path component safe for FAT: forbidden characters become '_', never empty or a dot name.
+std::string sanitize(const std::string& name);
+
+// "/irc/libera/#roro/2026-10-02.log" from {"irc", "libera", "#roro"} and a local date
+// ("YYYY-MM-DD"); an empty date (clock not set yet) gives "undated.log".
+std::string dailyLogPath(std::initializer_list<std::string> folders, const std::string& date);
+
+// Day number (days since 1970-01-01) encoded in a Log ("2026-10-02.log") or Capture
+// ("20261002-144500.pcap") file name, or -1 if the name carries no valid date.
+int fileDay(const std::string& fileName);
+
+int dayFromUtc(int64_t utcSeconds);
+
+}  // namespace roro::storage