Fix CSRF exemption and array-input crash on revocation/introspection

An Opus code review of the branch caught two real bugs the test suite
structurally couldn't see:

- /revocation and /introspect were never added to bootstrap/app.php's
  CSRF except list, so both were fully broken (403) for any real
  external client, despite every feature test passing — CSRF
  verification is short-circuited entirely while running tests.
  Verified live against the running app before and after the fix, and
  added a regression test that asserts against the actual configured
  exemptions rather than relying on request-time behavior that tests
  can't exercise.

- An array-shaped `token` param (e.g. token[]=a&token[]=b) crashed
  both endpoints with a 500, since this app promotes PHP warnings
  ("Array to string conversion") to exceptions. Fixed at the shared
  root, MicropubToken::findActive(), which also closes the same latent
  hole in VerifyMicropubToken's access_token param that predates this
  branch. Verified live and covered with regression tests.

Also applied the review's lower-severity findings: added the missing
introspection_endpoint Link header and metadata test assertions,
removed the now-dead is_string($scopes) array branch in the Micropub
handlers and media controller (scope is unconditionally a string from
the DB now, this guarded against a JWT-array-claim shape that can no
longer occur), dropped a redundant #[Table] model attribute, sized
token_hash to its actual 64-char length, and removed a one-off inline
style in the admin view.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014625MfkGZ7GVdbqKme4a8L

app/Services/Micropub/Handlers/CardHandler.php

@@ -24,9 +24,7 @@ class CardHandler implements MicropubHandlerInterface
         assert($data instanceof CardData);
 
         $scopes = $data->tokenData['scope'];
-        if (is_string($scopes)) {
-            $scopes = explode(' ', $scopes);
-        }
+        $scopes = explode(' ', $scopes);
 
         if (! in_array('create', $scopes, true)) {
             throw new InvalidTokenScopeException;