feat: slskd reconnect guard in downloaders_reset, mass v2 sync

- downloaders_reset: connection check block before slskd API sections;
  triggers PUT /api/v0/server reconnect if disconnected, polls 60s,
  gates Stuck Searches and Dead Transfer Records on SLSKD_CONNECTED
- Sync all modified/new/deleted files from v2 refactor across Docker_Essentials,
  Media, Monitors, Partnership, Rsync, Tools, Transcodes, unRAID_Essentials,
  common.sh, master confs, and new Manual/README docs

unRAID_Essentials/php_fpm_max_children.sh

@@ -2,53 +2,91 @@
 # ==============================================================================================
 # ============================= PHP-FPM Max Children ===========================================
 # ==============================================================================================
-# Persistently sets PHP-FPM pm.max_children on unRAID to prevent WebGUI slowdowns.
-# Run once at array start via ARRAY_START_SCRIPTS in master.conf.
-# Idempotent — completely silent when value is already correct.
 #
-# ── WHY THIS EXISTS ───────────────────────────────────────────────────────────────────────────
-# unRAID's WebGUI runs through PHP-FPM. The default pm.max_children is very low (4-8).
-# Under load — multiple users, Docker operations, heavy dashboard usage — all PHP workers
-# saturate and new requests queue. The WebGUI becomes slow or unresponsive.
+# PURPOSE
+# ─────────────────────────────────────────────────────────────────────────────
+# Raises PHP-FPM pm.max_children to prevent WebGUI slowdowns under load. Run
+# once at array start via ARRAY_START_SCRIPTS. Idempotent — silent when the
+# value is already correct, no restart on clean boot.
 #
-# pm.max_children controls how many PHP worker processes can run simultaneously.
-# Raising it allows the WebGUI to handle more concurrent requests without queuing.
-# Too high: wastes RAM. Too low: WebGUI slowdowns.
-# PHP_MAX_CHILDREN=250 is appropriate for 128GB — ~2MB per worker = ~500MB total.
+# unRAID's WebGUI runs through PHP-FPM. The default pm.max_children is very
+# low (4–8). Under load — multiple users, Docker operations, heavy dashboard
+# usage — all PHP workers saturate and new requests queue. The WebGUI becomes
+# slow or unresponsive.
 #
-# ── WHY IDEMPOTENT ────────────────────────────────────────────────────────────────────────────
-# This runs at every array start. If the value is already correct there is nothing to do —
-# no config write, no PHP-FPM restart. Restarting PHP-FPM unnecessarily disrupts active
-# WebGUI sessions and is annoying on every boot.
+# PHP_MAX_CHILDREN=250 is appropriate for 128GB RAM: ~2MB per worker = ~500MB
+# total. Too high wastes RAM; too low causes slowdowns.
 #
-# ── APPLY SEQUENCE ────────────────────────────────────────────────────────────────────────────
+# ==============================================================================================
+# DESIGN PRINCIPLES
+# ==============================================================================================
+#
+# Idempotent Content Check
+#   Reads the current pm.max_children value before writing. If already at
+#   target → silent exit, no PHP-FPM restart. Restarting PHP-FPM unnecessarily
+#   disrupts active WebGUI sessions on every boot.
+#
+# Pattern Match Before Write
+#   Verifies the sed pattern finds pm.max_children in the config before
+#   applying any change. Prevents silent failures where sed succeeds but
+#   writes nothing because the key was missing or commented out.
+#
+# Apply Sequence
 #   1. Read current pm.max_children from PHP_CONF
-#   2. If already at target → exit silently (idempotent)
+#   2. If already at target → exit silently
 #   3. Verify sed pattern matches before writing
 #   4. Apply sed replacement
 #   5. Restart PHP-FPM via rc.php-fpm
 #   6. Verify PHP-FPM process running after restart
-#   7. Verify config file reflects target value
+#   7. Read back config to confirm value applied
 #
-# ── SAFEGUARDS ────────────────────────────────────────────────────────────────────────────────
-#   Root check          — writing to system config requires root
-#   acquire_lock        — prevents concurrent runs at array start
-#   Idempotent check    — only restarts PHP-FPM when value actually changes
-#   Pattern match check — verifies sed found pm.max_children before writing
-#   Process verify      — confirms PHP-FPM running after restart
-#   Config verify       — reads back config to confirm value applied
-#   validate_unraid     — notify validated before use
-#   Silent on correct   — runs every boot, no noise when already set ✅
+# ==============================================================================================
+# OPERATIONAL SAFEGUARDS
+# ==============================================================================================
 #
-# ── CONFIGURATION (master.conf) ───────────────────────────────────────────────────────────────
-#   PHP_MAX_CHILDREN — target pm.max_children value (default 250)
-#   PHP_CONF         — path to PHP-FPM www.conf (default /etc/php83/php-fpm.d/www.conf)
+# Root Required
+#   Writing to /etc/php83/ requires root.
+#
+# Single Instance Lock
+#   acquire_lock prevents concurrent runs at array start.
+#
+# Process Verify
+#   Confirms PHP-FPM running after restart — errors if it failed to start.
+#
+# Config Verify
+#   Reads back config after restart to confirm the value was actually applied.
+#
+# Silent on Success
+#   Runs every boot — no noise when already correct.
+#
+# ==============================================================================================
+# CONFIGURATION
+# ==============================================================================================
+#
+# master.conf
+#
+#   PHP_MAX_CHILDREN
+#       Target pm.max_children value. (default: 250)
+#
+#   PHP_CONF
+#       Path to PHP-FPM www.conf. (default: /etc/php83/php-fpm.d/www.conf)
+#
+# ==============================================================================================
+# RUNTIME MODES
+# ==============================================================================================
+#
+# php_fpm_max_children.sh
+#     Read current value. Update and restart PHP-FPM only if changed. Silent if correct.
+#
+# php_fpm_max_children.sh --dry-run
+#     Show current vs target value. No config write or restart.
+#
+# php_fpm_max_children.sh --status
+#     Show current pm.max_children, target, and PHP-FPM process state.
+#
+# php_fpm_max_children.sh --log
+#     Verbose output showing idempotent check, config write, and restart result.
 #
-# ── USAGE ─────────────────────────────────────────────────────────────────────────────────────
-#   php_fpm_max_children.sh              — normal run (idempotent)
-#   php_fpm_max_children.sh --dry-run    — show what would change
-#   php_fpm_max_children.sh --status     — show current vs target and process state
-#   php_fpm_max_children.sh --log        — verbose output
 # ==============================================================================================
 
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"