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

Media/playback_aware_radarr_discovery.sh

@@ -84,6 +84,33 @@
 # Recommended schedule: weekly (WEEKLY_MAINTENANCE_SCRIPTS in master.conf)
 #
 # ==============================================================================================
+# OPERATIONAL SAFEGUARDS
+# ==============================================================================================
+#
+# Root Required
+#   acquire_lock and Radarr API writes require root. Script exits cleanly if not root.
+#
+# Dry-Run Mode
+#   --dry-run scores and ranks all candidates but makes no Radarr API calls and does not
+#   write to the history file. Safe to run at any time to preview what would be added.
+#
+# Add-Only
+#   Only adds movies to Radarr. Never deletes or modifies existing entries.
+#
+# Cooldown Guard
+#   Candidates rejected this run are recorded in the history file and not re-evaluated
+#   until RADARR_DISCOVERY_REJECT_COOLDOWN days have elapsed.
+#
+# ==============================================================================================
+# STATE FILES
+# ==============================================================================================
+#
+#   RADARR_DISCOVERY_HISTORY (default: $DATA_DIR/radarr_discovery_history.db)
+#     Tracks added movies and rejected candidates with timestamps. Written after every
+#     non-dry-run. Enforces reject cooldown and prevents re-adding items added by previous
+#     runs. Safe to delete — next run starts fresh with no memory.
+#
+# ==============================================================================================
 
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"