feat(issues): retry a processing issue through the individual scanner

POST /api/libraries/:id/issues/:issueId/retry (admin, family-lens gated
via the existing gateIssue) re-runs the work that produced an open issue
— deliberately NOT a library-wide rescan. Two shapes mirror the two
ledger entry kinds:

- item-backed issues rescan their media item through the book-detail
  RescanMediaItem mechanism (self-resolving folders, multi-file
  audiobook routing, write-after-success guards) and then close the
  issue (RetryMediaItemIssue);
- row-less import_failed issues re-import the single file through the
  watcher's standalone processMediaFile path (RetryFailedImport: folders
  resolved RescanMediaItem-style so paths stay library-root-relative),
  whose create-path self-heal plus an explicit path resolve closes the
  issue even when the content was already imported by a prior attempt.

Failures return the REAL underlying error so the UI can show why the
issue still exists; a vanished file is a 409 (ErrRetryFileMissing);
already-resolved issues reject re-retry.

Docs + bruno mirrors regenerated for the new route (the generator's seq
renumbering touches three unrelated bruno files as fallout; openapi
gains the path and the date bump), and the docs schema registry gains
the retry entry so TestDocsMatchRoutes passes.

bruno/libraries/retry_processing_issue.yml

@@ -0,0 +1,23 @@
+info:
+  name: Retry Processing Issue
+  type: http
+  seq: 18
+
+http:
+  method: POST
+  url: '{{base_url}}/api/libraries/{{ebook_library_id}}/issues/{{issueid}}/retry'
+  auth: inherit
+settings:
+  encodeUrl: true
+  timeout: 0
+  followRedirects: true
+  maxRedirects: 5
+
+docs:
+  content: |-
+    # Retry Processing Issue
+
+    `POST /api/libraries/:id/issues/:issueId/retry` — auth: jwt+admin.
+
+    Canonical reference: docs/developer/api/libraries/retry_processing_issue.md (docs site → Developer → API). This request is GENERATED from that doc; edit the doc, then run the drift test with -update.
+  type: text/markdown

bruno/libraries/set_library_visibility.yml

@@ -1,7 +1,7 @@
 info:
   name: Set Library Visibility
   type: http
-  seq: 19
+  seq: 20
 
 http:
   method: POST

bruno/libraries/update_library.yml

@@ -1,7 +1,7 @@
 info:
   name: Update Library
   type: http
-  seq: 20
+  seq: 21
 
 http:
   method: PUT

bruno/libraries/update_scan_settings.yml

@@ -1,7 +1,7 @@
 info:
   name: Update Scan Settings
   type: http
-  seq: 21
+  seq: 22
 
 http:
   method: PUT