fix(catalog): survive an unreachable registry, and ask for the gap (#3299)

Serve an expired registry cache when revalidation fails, so one timeout against the registry host no longer reports the whole catalog as unreachable while a usable copy sits on disk.

Hand back the gap-report command at the moment a search comes back wrong: catalog --query prints it pre-filled on both tiers, and every --json search envelope carries it as report_gap. Report on either tier, since the on-device tier needs a consented download and every gap reported to date came from the word tier.

Document the gap channel in the registry skill, which owns hyperframes catalog and never mentioned it, and name the CLI commands no skill did.

skills/hyperframes-registry/SKILL.md

@@ -110,12 +110,30 @@ npx hyperframes catalog --human-friendly
 
 The normal table and `--json` modes only list matches; install a selected name with `hyperframes add <name>`. `--human-friendly` opens an interactive picker and installs the selected item immediately. In CI or agent workflows, prefer `--json` followed by an explicit `add`.
 
+### Report what the catalog does not have
+
+When the search comes back and nothing in it does the job, say so before you hand-author the move:
+
+```bash
+npx hyperframes feedback --search-miss "<the query you ran>" --wanted "<the move you needed>" --tier on-device
+```
+
+`catalog --query` prints this line for you, pre-filled, and `--json` carries it as `report_gap` — so it is already in hand at the moment you decide nothing fits.
+
+**Report whenever nothing in the results does the job, on either tier.** Do not wait for the on-device tier to have answered: it needs a consented 33 MB download, so an agent run is on `words` unless it explicitly opted in, and gating on `on-device` would silence almost every report. The `--tier` value rides along so a vocabulary miss stays distinguishable from a meaning miss when these are read. Describe the effect you wanted, not the item name you imagined: what comes back is a list of moves worth building, and a report naming a non-existent item teaches nothing. This is the only path that sends a query anywhere, which is exactly why it is a separate deliberate command rather than something the search does on its own. It carries no rating and never lands in the rating metric.
+
+This is the whole demand signal for the catalog. Skipping it means the gap you hit gets guessed at from install counts instead, which cannot see a move nobody could install.
+
 If the CLI cannot reach the configured registry, inspect the raw manifest as a fallback:
 
 ```bash
 curl -s https://raw.githubusercontent.com/heygen-com/hyperframes/main/registry/registry.json
 ```
 
+A registry the CLI cannot reach does **not** empty the catalog for **discovery**: a previously fetched manifest keeps serving past its 24h refresh window whenever revalidation fails, so `catalog` and `catalog --query` still list and rank against the last copy on disk.
+
+**`add` still needs the network, even for an item you installed yesterday.** Only manifests are cached; the item's actual files are fetched on every install. So offline you can search, and you can see what an item is, but installing it fails at the file fetch. Do not promise a user an offline install.
+
 Each item's `registry-item.json` contains: name, type, title, description, tags, dimensions (blocks only), duration (blocks only), and file list.
 
 See [discovery.md](./references/discovery.md) for details on filtering by type and tags.