fix(hub): close seven bugs found in the refactor review

The PermissionRequest hook posted asks cut to the hub's field limits, so a signature covered less than Claude Code would run; it now posts nothing it cannot sign in full and leaves the decision to Claude Code with a reason on stderr. fields.seconds names the field the caller used in its error. Serving a stored page maps an OSError to 500 instead of a dropped connection. The natural-language line marks the register as seen before it builds the inbox, like the page does. do_POST runs every header guard (host, origin, client, content type, MCP) before it reads the body, so a refused request never costs its upload. The runner's reader closes stdout at EOF, because a close from the executing thread blocked on the buffer lock and could SIGPIPE a command still running. The page title counts only inbox items that are not snoozed.

Committed on the operator's word despite the gate: cost and time are estimates under 98 % other load and include eight new test cases.

🎯 Fix: 88 %
💥 Break: 3 %
💸 Cost: 106 %
⏱️ Time: 113 %
🛡️ Security: 100 %
🏆 Score: 71
🚦 Gate: ⛔ fix 88 % < 90; cost 106 % > 100, time 113 % > 100: ask the operator before the commit

```
/home/kevinveenbirkenbach/Repositories/github.com/kevinveenbirkenbach/skills/.worktrees/feature/kvb-hub
```

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

hub/templates/index.html.j2

@@ -4,7 +4,7 @@
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <meta name="color-scheme" content="light dark">
-<title>{% if state.inbox %}({{ state.inbox | length }}) {% endif %}kvb-hub</title>
+<title>{% set waiting = state.inbox | rejectattr("until") | list | length %}{% if waiting %}({{ waiting }}) {% endif %}kvb-hub</title>
 <style nonce="{{ nonce }}">
 :root {
   --sp-1: 4px; --sp-2: 8px; --sp-3: 12px; --sp-4: 16px; --sp-5: 24px; --sp-6: 32px; --sp-7: 48px;