fix: address ds-review-bot v8 findings

- llm-deepseek: the uncatalogued resolveModel fallback declares text-only
  modalities — the wire route is text-only regardless of catalog
  membership, so "unknown" must not let the host persist-then-fail images.
- session.selectModel also consults the pending-inbox mirror: a queued
  image prompt enters the log only when claimed, after a switch would land.
- attachment store: ensureDurableDirectory syncs every ancestor entry up to
  a caller-vouched boundary regardless of what mkdir reports — a raced
  "already existed" is not "already durable".
- One image walker (imageBlockIn/imageInEvent) now serves both attachment
  authorization and the selection gate; referencedImage therefore also
  authorizes references inside wrapped message content.
- InputHub: the scope disposer resolves the conversation service optionally
  (teardown/HMR must reach quiescence), and a send failing after its scope
  died releases the in-flight drafts instead of restoring them onto a
  disposed shell.
- http-bridge destroys declared-oversize requests with connection: close
  instead of draining a body the client can trickle indefinitely.
- LlmService validates AND detaches modality arrays identically on the
  advisory and exact routes; READMEs record the fourth INVALID_MODEL_INFO
  rejection reason.
- CLI provider docs (JSDoc, README pair, Agent Note pair) describe the
  reuse behavior; llm-route.spec now parses the SHIPPED cordis.yml through
  the production extraction, pinning the row coupling.
- image-display lane pins gallery/rail shape in inline snapshots and the
  object-URL scheme this environment must take; stale host.schema comment
  dropped.

packages/host/apiproxy/src/api/host.schema.ts

@@ -37,8 +37,6 @@ export const hostDescribeValueSchema = z.object({
     mediaTypes: z.array(imageMediaTypeSchema),
   }).optional(),
   attachedSessions: z.number().int().nonnegative(),
-  // Open string, not a literal union: unknown kinds must survive the wire so
-  // a merge-added capability can advertise (the client hides the affordance).
 }) satisfies z.ZodType<Wire<ResponseValue<'host.describe'>>>
 
 /** host.pickDirectory request payload (empty object literal). */