hive-c0re: split OpenAPI summary/description, move param docs to params

utoipa splits a handler's doc comment on the first blank `///` line:
everything before it becomes the OpenAPI `summary` (shown in Swagger
UI's collapsed endpoint-list row), everything after becomes the
`description` (only shown once that row is expanded). With no blank
line, the whole doc comment becomes the summary and the description is
empty — which is what every handler in hive-c0re/src/dashboard/ was
doing, so the all-endpoints list showed full multi-sentence prose next
to every route instead of a short one-liner.

For every `#[utoipa::path(...)]`-annotated handler across the 19 files
in that module:

- Inserted a blank `///` line after the first short sentence/clause so
  utoipa's split produces a real summary + description, where the doc
  comment had more to say. Left already-short single-clause docs alone
  (nothing to split).
- Where a query struct derives `IntoParams`, moved param prose that
  duplicated a field's own doc comment out of the handler doc (the
  field already documents itself in the generated spec), or added a
  field doc where the handler explained a param that had none.

No behavior changes — doc comments and `params()` description text
only. Verified `cargo build -p hive-c0re` (clean) and `nix fmt` (zero
changes) after.

Closes #2969

hive-c0re/src/dashboard/webhook.rs

@@ -58,8 +58,10 @@ pub(super) struct PushWebhookRepo {
 }
 
 /// POST `/webhook/knowledge` — Forgejo push webhook for
-/// `internal/knowledge`. Runs `git pull` on the local clone so
-/// agents see up-to-date documents on their next turn.
+/// `internal/knowledge`.
+///
+/// Runs `git pull` on the local clone so agents see up-to-date documents
+/// on their next turn.
 ///
 /// Expected Forgejo webhook configuration:
 /// - URL: `https://<HYPERHIVE_HIVE_DOMAIN>/webhook/knowledge`