tlc: update PLAN.md with Sprint 5 F-series completion

local/recipes/tui/tlc/PLAN.md

@@ -6,6 +6,7 @@
 - Sprint 3 (C1–C18): medium polish
 - Sprint 4 / D-series (D1–D8): dialogs + mouse + multi-cursor + spell check
 - Sprint 5 / E-series (E1): F9 menu restructure for MC parity
+- Sprint 5 / F-series (F1–F4): chunked viewer rendering + xz2 + cleanup
 
 **Branch:** `0.2.5`
 **Tests:** 1369 passing (+150 across all sprints)
@@ -150,6 +151,7 @@ zero code changes. No `target_os = "redox"` or `target_os = "linux"` gates.
 | Sprint 3 (C1–C18 medium polish) | 10/18 + 7 N/A | ✅ Done | 2026-07-05 |
 | Sprint 4 / D-series (D1–D8) | 8/8 | ✅ Complete | — |
 | Sprint 5 / E-series (E1) | 1/1 | ✅ Complete | — |
+| Sprint 5 / F-series (F1–F4) | 4/4 | ✅ Complete | — |
 
 ### 3.2 Remaining LOW-priority items
 
@@ -214,6 +216,28 @@ All previously deferred items are now resolved:
 
 ## 4. RECENT CHANGELOG (last 6 months, condensed)
 
+### 2026-07-05 — Sprint 5 / F-series — chunked viewer, xz2, cleanup
+
+**F1 Stale comment cleanup:** Removed outdated "Phase N" / "not yet wired"
+comments from `vfs/local.rs`, `vfs/traits.rs`, `editor/usermenu.rs` — the
+functionality they described is already implemented.
+
+**F2 Chunked source viewer rendering:** Replaced placeholder stubs in
+`viewer/hex.rs` and `viewer/text.rs` with actual rendering for Chunked
+sources (files >= 1 MiB). Hex viewer reads viewport-sized chunks via
+`read_at()` with viewport-relative indexing. Text viewer reads up to
+64 MiB cap for line offset mapping. `check_growing()` in `viewer/mod.rs`
+also reads Chunked content instead of returning empty Vec.
+
+**F3 Editor Settings dialog:** Replaced "(TBD)" placeholder with actual
+toggle state display (auto-indent, word-wrap, show-whitespace, save-on-quit).
+
+**F4 tar.xz decompression:** Added `xz2` crate as optional dependency
+(feature-gated). `TarKind::Xz` now uses `XzDecoder::new_multi_decoder`
+for multi-stream `.tar.xz` files instead of returning `Unsupported`.
+
+1369 tests pass (default and with `--features xz2`).
+
 ### 2026-07-05 — Sprint 5 / E1 — F9 menu restructure for MC parity
 
 Rewrote `build_menus()` in `filemanager/menubar.rs` to match MC's