feat(tomesync): sync on suspend — morning stats without waking the device (build 35)

[bndct-devops]

Closes #128.

What

Two new opt-in TomeSync settings (both default off), plugin build 35 / semver 1.9.0:

• Sync on suspend — when the device goes to sleep, catch up anything still pending: queued sessions, queued ratings, and (when "Auto-sync reading history on launch" is enabled) the KOReader reading-history backfill. Only syncs when WiFi is already connected.
• Aggressive sync (turn WiFi on at suspend) — gated on the first toggle. If the radio is off at suspend, bring it up via NetworkMgr:turnOnWifiAndWaitForConnection, sync, and let the system power it back down as the device sleeps. For devices that aggressively sleep the radio (the reporter's PocketBook).

Plus one unconditional improvement: onNetworkConnected now also runs the reading-history backfill (previously launch-only, so morning WiFi-on didn't refresh stats without restarting KOReader) and no longer requires an open book to flush pending state — WiFi coming up in the file manager catches everything up.

Design notes

• The aggressive path deliberately bypasses beforeWifiAction/wifi_enable_action: with the default "prompt" setting, honoring it would pop a connect dialog onto the sleep screen (the footgun stock KOSync warns about and makes the user reconfigure around). The toggle's promise is "turn WiFi on", so it does exactly that.
• The whole suspend path is queue-or-resume safe by construction — sessions/ratings re-flush from their pending queues, and the history import resumes from the server-side watermark — so a device that finishes suspending mid-sync (or before WiFi associates) just completes on the next connection. First-run backfills won't fit in a suspend window; they make partial progress and resume. That's the accepted trade-off, documented in the toggle help text.

Verification

• Full backend suite green (922 passed); the semver-pin test updated for 1.9.0.
• Emulator round-trip on this branch (fake-WiFi + Suspend broadcast):
  • WiFi up + suspend → history sync runs (watermark GET observed server-side)
  • WiFi down + aggressive → radio comes up, sync completes ~2s later on NetworkConnected
  • Toggles off (default) → suspend is a no-op, byte-identical to current behavior
  • Aggressive toggle correctly disabled while the master toggle is off
• Not yet validated on real hardware. The aggressive path is device-specific; plan is to ask the reporter (PocketBook Era) to validate via [KOReader Plugin] Sync on suspend #128 after merge, plus a Kindle pass before release.