feat: wire capability tokens and the audit trail through CLI, REPL and web

The risk model, grants and hash-chained trail existed as modules nothing
called. Now every engagement runs under them.

Capability
- `neurosploit capability issue|verify` mints and inspects grants.
- `--capability-token` (global, so the REPL takes it too), `--in-scope`,
  `--environment`, `--policy` on `run`; verification happens at the command
  line, so an invalid grant fails with a readable message instead of halfway
  through an engagement.
- The pipeline verifies before anything else and REFUSES to run on a token that
  does not verify — proceeding would mean acting on an authorization nobody can
  prove was issued. `effective_scope` then applies the grant as a ceiling.
- Web: an Authorization tab carrying the token, extra hosts, environment and
  policy profile. The browser decodes the claims for display and says plainly
  that it is not verifying them — a "valid" badge from a party without the key
  would be the UI vouching for something it cannot check.

A hole the smoke test found: `/inscope evil.test` inside a session under a
grant WIDENED the scope past it — the one thing a capability token exists to
prevent. The run itself would still have been constrained (the pipeline
re-applies the grant), but `/policy` reported a boundary that was not real, and
a tool that misreports its own limits is worse than one with none. Scope
mutations now re-apply the ceiling and name what it refused. Session
authorization also arrives from argv rather than a `/`-command, because a
session that can widen its own grant is not constrained by one.

Audit
- One hash-chained record per action in `<run>/audit.jsonl`, in the specified
  shape, covering engagement start/end, validator rejections, findings that
  reach the report (with the hash of the evidence behind them) and findings
  withheld for being out of scope.
- The run verifies its own chain at the end and says loudly if it is broken.
- `/audit [n]` tails the trail and verifies it; the web offers it as a download
  next to the report, so "show me what the tool did" is a link.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

web/public/style.css

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