docs sync + revert auto-unfree removal

revert the earlier 'operator must set allowUnfree' move:
per-agent containers evaluate their own nixpkgs and the operator's
host-level allowUnfree doesn't propagate in. restoring the scoped
allowUnfreePredicate inside both the claude-unstable overlay and
harness-base.nix; documented in README + gotchas as 'nothing to
set on the operator side'.

docs:
- claude.md file map adds crash_watch.rs, kick_agent on coordinator,
  /api/model + journald viewer + bind-with-retry references.
- scratchpad rewritten to reflect the recent run.
- web-ui.md: notification row + browser notifications section,
  state row (badge + model chip + last-turn chip + cancel button),
  per-agent inbox, /model slash, /cancel-question + journald
  endpoints, focus-preservation on refresh.
- turn-loop.md: --model is read from Bus::model() per turn (runtime
  override via /model); recv(wait_seconds) up to 180s with the
  rationale; ask_operator gains ttl_seconds; new TurnState section;
  kick_agent inbox-on-startup hint.
- approvals.md: ttl/cancel resolution paths for operator questions.
- persistence.md: /state/hyperhive-model file.
- gotchas.md: web UI port collision policy (rename, don't probe);
  bind retry + SO_REUSEADDR shape; auto-unfree restored.
- todo.md: cleaned up empty sections and stale entries; /model
  shipped, dropped from the list.

README.md

@@ -91,16 +91,12 @@ hive-c0re will then:
 - auto-create the manager container (`hm1nd`) if missing,
 - auto-rebuild any managed container whose hyperhive rev is stale.
 
-`claude-code` is unfree; hyperhive does not auto-allow it for you.
-Add to your host config:
-
-```nix
-nixpkgs.config.allowUnfreePredicate =
-  pkg: builtins.elem (nixpkgs.lib.getName pkg) [ "claude-code" ];
-```
-
-(or `nixpkgs.config.allowUnfree = true`, your call). Each per-agent
-container inherits this through the same nixpkgs evaluation.
+`claude-code` is unfree; hyperhive whitelists it for itself
+(scoped: only `claude-code`, nothing else) inside the
+`claude-unstable` overlay and `harness-base.nix`. Per-agent
+containers evaluate their own nixpkgs instance so the operator's
+host-level `allowUnfree` doesn't propagate in — the predicate has
+to live inline. Nothing to set on the operator side.
 
 ## Build / deploy