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.cpp

@@ -0,0 +1,67 @@
+#include "storage_paths.h"
+
+#include <cctype>
+
+namespace roro::storage {
+
+namespace {
+
+// Howard Hinnant's days_from_civil.
+int daysFromCivil(int y, int m, int d) {
+    y -= m <= 2;
+    int era = (y >= 0 ? y : y - 399) / 400;
+    int yoe = y - era * 400;
+    int doy = (153 * (m + (m > 2 ? -3 : 9)) + 2) / 5 + d - 1;
+    int doe = yoe * 365 + yoe / 4 - yoe / 100 + doy;
+    return era * 146097 + doe - 719468;
+}
+
+bool digits(const std::string& s, size_t pos, size_t n, int& out) {
+    if (pos + n > s.size()) return false;
+    out = 0;
+    for (size_t i = pos; i < pos + n; i++) {
+        if (!std::isdigit(static_cast<unsigned char>(s[i]))) return false;
+        out = out * 10 + (s[i] - '0');
+    }
+    return true;
+}
+
+int validDay(int y, int m, int d) {
+    static const int kDays[] = {31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
+    if (y < 1970 || m < 1 || m > 12 || d < 1 || d > kDays[m - 1]) return -1;
+    return daysFromCivil(y, m, d);
+}
+
+}  // namespace
+
+std::string sanitize(const std::string& name) {
+    std::string out;
+    for (char c : name) {
+        bool forbidden = c == '\\' || c == '/' || c == ':' || c == '*' || c == '?' || c == '"' || c == '<' ||
+                         c == '>' || c == '|' || static_cast<unsigned char>(c) < 0x20;
+        out += forbidden ? '_' : c;
+    }
+    if (out.empty() || out == ".") return "_";
+    if (out == "..") return "_.";
+    return out;
+}
+
+std::string dailyLogPath(std::initializer_list<std::string> folders, const std::string& date) {
+    std::string path;
+    for (auto& f : folders) path += "/" + sanitize(f);
+    return path + "/" + (date.empty() ? "undated" : date) + ".log";
+}
+
+int fileDay(const std::string& name) {
+    int y, m, d;
+    if (digits(name, 0, 4, y) && name.size() > 10 && name[4] == '-' && digits(name, 5, 2, m) && name[7] == '-' &&
+        digits(name, 8, 2, d))
+        return validDay(y, m, d);
+    if (digits(name, 0, 4, y) && digits(name, 4, 2, m) && digits(name, 6, 2, d) && name.size() > 8 && name[8] == '-')
+        return validDay(y, m, d);
+    return -1;
+}
+
+int dayFromUtc(int64_t utcSeconds) { return static_cast<int>(utcSeconds / 86400); }
+
+}  // namespace roro::storage