docs: v0.124.0 backups IA restructure — CHANGELOG + REPORT + CONTEXT (decisions 1-3) + README page map + REUSE; records the HIGH containerized-.fab volume-strand finding and the agent SystemDisks legacy-boot finding

Claude-Session: https://claude.ai/code/session_01GzammAMzsJTgpQHqxwM2bC

CHANGELOG.md

@@ -1,5 +1,45 @@
 ## Changelog
 
+### v0.124.0 — backups IA restructure: four sub-pages, Felhom-offsite status card, .fab browser download (2026-07-13) — MinAgent: 0.81.0
+
+The nine-section backups page split into four sub-pages (operator review: customers got lost);
+plus the offsite status card and the .fab portability exit. Controller-only; floor untouched.
+Operator decisions recorded in CONTEXT: single active offsite destination stands; the status
+card never changes state; .fab is portability, NOT a backup tier.
+
+- **IA split** (`backups{,_remote,_apps,_restore}.html` + `backups_shared.html` partials):
+  **Áttekintés** `/backups` (storage overview, Rendszermentés, stat cards, single-copy warning),
+  **Távoli mentés** `/backups/remote` (status card + toggles + manual-target form,
+  `#offbox-section` anchor), **Alkalmazások** `/backups/apps` (schedule, Adatbázisok, per-app
+  1./2./3. rows), **Visszaállítás** `/backups/restore` (restore panel, the RELOCATED offbox
+  restore-to-verify, the .fab loop). Sections MOVED verbatim — `scripts/backups_split_move_check.py`
+  compares all 15 blocks against the v0.123.0 baseline (red-proven). Shared data builder
+  extracted (`backupsCommonData` + `backupsOffboxData`) — no duplicated computation. Old links
+  survive: `/backups` = Áttekintés; tier-3 row actions → `/backups/remote#offbox-section`;
+  offbox/restore/tier2 flash redirects + the tier2-config back-link retargeted per page.
+- **Felhom-offsite status card** (top of Távoli mentés; local data only, DISPLAY-ONLY — no form,
+  no button, unit-enforced): (1) no target → "Felhom offsite tárhely — igényelhető szolgáltatás.
+  …Érdeklődj az üzemeltetőnél."; (2) applied + zero toggled → "Aktív — nincs kijelölt
+  alkalmazás" (+ the v0.123.0 hint below); (3) applied + toggled → no card (the status block is
+  the state). States 2 and 3 live-proven on the drill box.
+- **.fab browser download** (`handler_export_download.go`): the EXISTING async export pipeline
+  with dest = a staging dir under the data dir (`fab-downloads/`; same producer → byte-identical
+  bundle), estimate shown BEFORE start, then a guarded streaming exit
+  (`GET /api/export/download?file=` — basename-shape + dir-containment guard, red-proven against
+  prefix-only matching; `io.Copy`, `Content-Disposition: attachment`, post-stream removal, 1h TTL
+  sweep on startup + each start). Batch UI downloads apps ONE AT A TIME (no mega-zip). Import
+  stays drive-scan; portability copy on the section ("Hordozható pillanatfelvétel…").
+  Unit round-trip: real export → import → content equality; a corrupted bundle is REFUSED
+  (gzip CRC — there is no per-file checksum; documented).
+- **FINDINGS from the live §13 run** (both pre-existing, recorded for follow-up tasks):
+  **(HIGH)** containerized-controller .fab export of Docker-VOLUME apps strands the volume tar on
+  the GUEST host (`docker run -v <container-tmp>:/out` resolves against the host FS) → the bundle
+  ships an EMPTY `data/volumes`, export reports success, import brings the app up EMPTY. HDD-data
+  apps unaffected. Live-hit on demo (ActualBudget; data restored from the stranded tar by hand).
+  **(MEDIUM)** agent-side: on a legacy-boot PVE with LVM root, `SystemDisks` resolves NO raw
+  system disk → `sysKnown=false` → every disk classified system → the drive wizard can never
+  offer a candidate (drill box; hot-added disk invisible).
+
 ### v0.123.0 — polish batch: F-15 instant reset codes, F-11 inline confirms, Tier-3 "Távoli mentés" rename, zero-toggle honesty (2026-07-13) — MinAgent: 0.81.0
 
 Four independent fixes from the take-two drill + operator review. Live-validated on the drill box