feat(launcher): add sync command to merge stats and history between machines over SSH

subminer sync <host> exchanges VACUUM INTO snapshots over ssh/scp and each
side merges the other's data as an insert-only union keyed on session UUIDs,
video keys, series title keys, and word/kanji identity. Lifetime totals and
daily/monthly rollups are applied incrementally so pre-retention history
survives, remote-only historical rollups are copied, and re-syncing is
idempotent. sync --snapshot/--merge expose the underlying steps for manual
transfers; a pid-file/mpv-socket guard refuses to run while SubMiner may be
writing the database and schema-version mismatches abort the merge.

launcher/config/args-normalizer.test.ts

@@ -135,6 +135,14 @@ test('applyInvocationsToArgs maps config and jellyfin invocation state', () => {
     statsCleanupVocab: false,
     statsCleanupLifetime: false,
     statsLogLevel: null,
+    syncTriggered: false,
+    syncHost: null,
+    syncSnapshotPath: null,
+    syncMergePath: null,
+    syncRemoteCmd: null,
+    syncDbPath: null,
+    syncForce: false,
+    syncLogLevel: null,
     doctorTriggered: false,
     doctorLogLevel: null,
     doctorRefreshKnownWords: false,
@@ -181,6 +189,14 @@ test('applyInvocationsToArgs maps settings invocation to settings window', () =>
     statsCleanupVocab: false,
     statsCleanupLifetime: false,
     statsLogLevel: null,
+    syncTriggered: false,
+    syncHost: null,
+    syncSnapshotPath: null,
+    syncMergePath: null,
+    syncRemoteCmd: null,
+    syncDbPath: null,
+    syncForce: false,
+    syncLogLevel: null,
     doctorTriggered: false,
     doctorLogLevel: null,
     doctorRefreshKnownWords: false,
@@ -220,6 +236,14 @@ test('applyInvocationsToArgs fails when config invocation has no action', () =>
       statsCleanupVocab: false,
       statsCleanupLifetime: false,
       statsLogLevel: null,
+      syncTriggered: false,
+      syncHost: null,
+      syncSnapshotPath: null,
+      syncMergePath: null,
+      syncRemoteCmd: null,
+      syncDbPath: null,
+      syncForce: false,
+      syncLogLevel: null,
       doctorTriggered: false,
       doctorLogLevel: null,
       doctorRefreshKnownWords: false,
@@ -257,6 +281,14 @@ test('applyInvocationsToArgs maps texthooker browser-open request', () => {
     statsCleanupVocab: false,
     statsCleanupLifetime: false,
     statsLogLevel: null,
+    syncTriggered: false,
+    syncHost: null,
+    syncSnapshotPath: null,
+    syncMergePath: null,
+    syncRemoteCmd: null,
+    syncDbPath: null,
+    syncForce: false,
+    syncLogLevel: null,
     doctorTriggered: false,
     doctorLogLevel: null,
     doctorRefreshKnownWords: false,