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/cleanup_plan.cpp

@@ -0,0 +1,53 @@
+#include "cleanup_plan.h"
+
+#include <cstdio>
+
+#include "storage_paths.h"
+
+namespace roro {
+
+namespace {
+int maxAgeDays(CleanupAge age) {
+    switch (age) {
+        case CleanupAge::OneMonth: return 30;
+        case CleanupAge::ThreeMonths: return 91;
+        case CleanupAge::SixMonths: return 182;
+        case CleanupAge::OneYear: return 365;
+        default: return -1;
+    }
+}
+}  // namespace
+
+CleanupPlan CleanupPlan::make(const std::vector<StoredFile>& files, CleanupAge age, int todayDay) {
+    CleanupPlan plan;
+    for (auto& f : files) {
+        if (f.path.rfind("/notes", 0) == 0) continue;  // Notes are never cleaned up
+        bool selected = age == CleanupAge::Everything;
+        if (!selected) {
+            size_t slash = f.path.find_last_of('/');
+            int day = storage::fileDay(slash == std::string::npos ? f.path : f.path.substr(slash + 1));
+            selected = day >= 0 && todayDay - day > maxAgeDays(age);
+        }
+        if (selected) {
+            plan.paths.push_back(f.path);
+            plan.bytes += f.bytes;
+        }
+    }
+    return plan;
+}
+
+std::string formatBytes(uint64_t bytes) {
+    const char* units[] = {"B", "KB", "MB", "GB"};
+    double v = static_cast<double>(bytes);
+    int u = 0;
+    while (v >= 1024 && u < 3) {
+        v /= 1024;
+        u++;
+    }
+    char buf[16];
+    if (u == 0 || v >= 10) std::snprintf(buf, sizeof(buf), "%.0f %s", v, units[u]);
+    else std::snprintf(buf, sizeof(buf), "%.1f %s", v, units[u]);
+    return buf;
+}
+
+}  // namespace roro