Flip fallback coverage model: each host defines its own recovery profile

Previously HOST1 defined what it would run for HOST2 (FALLBACK_HOST1_COVERS_HOST2_TIER*).
Now each host defines what it wants run when IT goes down (FALLBACK_HOST1_TIER*), and the
covering server reads the down host's conf via the RAM/persistent cache.

get_tier_containers() reads FALLBACK_${REMOTE_ID}_TIER* instead of
FALLBACK_${MY_ID}_COVERS_${REMOTE_ID}_TIER*. Tier data migrated to the correct host confs.
Writeback paths and delays were already REMOTE_ID-based — no change needed there.

Deployment/host.conf.template

@@ -40,8 +40,8 @@
 #   ── FALLBACK ───────────────────────────────────────────────────────────────────────────────
 #   DDNS                    DDNS containers managed by this host
 #   INTERNET LOSS           containers stopped when internet is lost
-#   FALLBACK TIERS          what this host runs for the remote per tier
-#   TIER DELAYS             delays before each tier activates
+#   FALLBACK TIERS          what this host wants the partner to run when this host is down
+#   TIER DELAYS             how long this host must be down before each tier activates
 #   RSYNC WRITEBACK         appdata synced back on handback
 #
 #   ── DOCKER ─────────────────────────────────────────────────────────────────────────────────
@@ -255,27 +255,27 @@
         # "MyServer.com"
     )
 
-# ━━━ Fallback Tiers — HOSTN Runs for Partner ━━━
-# Containers this host starts when the partner goes down.
-# Replace REMOTE_ID below with the actual remote host ID (HOST1, HOST2, etc.)
-    FALLBACK_HOSTN_COVERS_REMOTE_ID_TIER1=(
-        # "Partner-DDNS-Container"
+# ━━━ Fallback Tiers — What HOSTN Wants Covered When Down ━━━
+# Containers the partner starts for HOSTN when HOSTN goes down.
+# Tier 1 is always immediate. Higher tiers activate after HOSTN_TIER*_DELAY minutes.
+    FALLBACK_HOSTN_TIER1=(
+        # "MyServer-DDNS-Container"
     )
 
-    FALLBACK_HOSTN_COVERS_REMOTE_ID_TIER2=(
+    FALLBACK_HOSTN_TIER2=(
         # "container-placeholder"
     )
 
-    FALLBACK_HOSTN_COVERS_REMOTE_ID_TIER3=(
+    FALLBACK_HOSTN_TIER3=(
         # "container-placeholder"
     )
 
-    FALLBACK_HOSTN_COVERS_REMOTE_ID_TIER4=(
+    FALLBACK_HOSTN_TIER4=(
         # "container-placeholder"
     )
 
-# ━━━ Tier Delays — This Host's Outage Timers ━━━
-# How long THIS host must be down before each tier activates on the partner.
+# ━━━ Tier Delays — HOSTN Outage Timers ━━━
+# How long HOSTN must be down before each tier activates on the partner.
     HOSTN_TIER2_DELAY=240           # 4 hours
     HOSTN_TIER3_DELAY=720           # 12 hours
     HOSTN_TIER4_DELAY=1440          # 24 hours