rename: failover → fallback throughout codebase — this system is Fallback, state is FALLBACK; preserve conventional failover comparisons

Rsync/Manual-Rsync.md

@@ -68,7 +68,7 @@ Terminal access                   — unRAID UI → Tools → Terminal, or SSH
 Optional but recommended:
 ```
 Gitea (Docker container on HOST1)  — self-hosted git for the script repository
-Working Emby installation          — for transcode management and failover
+Working Emby installation          — for transcode management and fallback
 ```
 
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@@ -366,7 +366,7 @@ PROFILES["emby-fallback_REMOTE_RESTART_CONTAINERS"]=("Emby")
 - Why: WAL is checkpointed on clean shutdown — safe to copy everything
 - Result: HOST2 gets a gold-standard Emby state once per week
 
-The two profiles work together. emby-fallback keeps HOST2 current for immediate failover.
+The two profiles work together. emby-fallback keeps HOST2 current for immediate fallback.
 emby gives HOST2 full fidelity once per week. Neither alone is sufficient.
 
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