Docs pass: update headers and READMEs for all new scripts

Script headers (6 files):
- Add OPERATIONAL SAFEGUARDS section to all discovery + emby sync scripts
- Add STATE FILES section to all 3 discovery scripts
- Add CONFIGURATION section to emby_to_*_sync.sh
- Rename USAGE → RUNTIME MODES in emby_to_*_sync.sh (doc standard)
- Fix SONARR_DISCOVERY_MONITOR_MODE default doc: "future" → "all"

Media/README-Media.md:
- Remove "WIP prototype" label; describe all 3 discovery scripts
- Add discovery scripts to scripts table and HOW THE SCRIPTS RELATE diagram
- Add weekly discovery schedule block to EXECUTION ORDER section
- Update intro to mention behavior-driven discovery

Media/Manual-Media.md:
- Add configuration reference sections for all 3 discovery scripts
- Add flag reference sections for all 3 discovery scripts

Tools/README-Tools.md:
- Add "Library Sync Bootstrap" category and emby_to_*_sync.sh to scripts table
- Add emby sync scripts to HOW THE SCRIPTS RELATE diagram

Tools/Manual-Tools.md:
- Update emby sync notes: search commands now fire immediately after add

README.md:
- Update Media folder description to include discovery
- Update weekly schedule to show discovery scripts
- Update README table entry for Media

Tools/emby_to_lidarr_sync.sh

@@ -21,12 +21,33 @@
 #   3. For each played artist not in Lidarr → add to Lidarr
 #
 # ==============================================================================================
-# USAGE
+# OPERATIONAL SAFEGUARDS
 # ==============================================================================================
 #
-#   emby_to_lidarr_sync.sh             — add all played artists not in Lidarr
+# Root Required
+#   acquire_lock requires root. Script exits cleanly if not root.
+#
+# Dry-Run Mode
+#   --dry-run shows all artists that would be added without making any Lidarr API calls.
+#   Always run first when closing the gap after a fresh Lidarr install or database wipe.
+#
+# Add-Only
+#   Only adds artists to Lidarr. Items already tracked (by name) are skipped without
+#   modification. Safe to run multiple times — the second run finds nothing to add.
+#
+# ==============================================================================================
+# CONFIGURATION (master_host*.conf)
+# ==============================================================================================
+#
+#   HOST*_LIDARR_URL / HOST*_LIDARR_API_KEY    — Lidarr connection (aliased by detect_hosts)
+#   HOST*_EMBY_URL   / HOST*_EMBY_API_KEY      — Emby connection (aliased by detect_hosts)
+#
+# ==============================================================================================
+# RUNTIME MODES
+# ==============================================================================================
+#
+#   emby_to_lidarr_sync.sh             — add all album artists not in Lidarr
 #   emby_to_lidarr_sync.sh --dry-run   — show what would be added, no changes
-#   emby_to_lidarr_sync.sh --days N    — limit to plays in the last N days
 #   emby_to_lidarr_sync.sh --log       — verbose output
 #
 # ==============================================================================================