docs: align all markdown docs with current code (v0.6.1)

- CHANGELOG: add entries #47 (is_selected/is_valid fee bounds, extremes allowed) and #48 (merge_will crash fix on missing date_to_check)
- HANDOFF: Electrum 4.7.2 and 4.8.0, current layout (qt.py, plugin.py, wallet_util/, docs/, bal_cli.py, 36-file ZIP), runtime/lint venv paths, standalone-script tests (427 collected), direct-to-main workflow, version history up to v0.6.1
- README: drop VERSION from layout, correct anticipate/expire/postpone behavior, update test commands
- docs/manual/README.md: fix Tools menu label to Will-Executors, add BASIC/ADVANCED notes, extend chromatic status table (Partially signed, Updated)
- docs/inheritance-options.md: add PARTIALLY_SIGNED status/transition/colour, version note to v0.6.1
- docs/README.md: make HTML-hosting instructions host-agnostic
- bal/README.md: Prepare button lives on the WILL tab

bal/README.md

@@ -12,8 +12,8 @@ servers.
   already-signed will is handled safely. Postponing a signed/sent will first
   asks you to invalidate the old transaction on-chain (so a will-executor can
   never broadcast the earlier-locktime transaction and execute the inheritance
-  too early), then lets you rebuild and re-send the new one via
-  **Tools → Prepare**.
+  too early), then lets you rebuild and re-send the new one via the
+  **Prepare** button on the **WILL** tab.
 - **"Server" column**: the will transaction list shows whether each transaction
   is actually stored on the will-executor servers
   (`Confirmed on server`, `Sent (not checked)`, `Send failed`,