feat(skill): layer the host skill registry per scope like the tools registry

The skills capability moves back to the host plane as one singleton, layered
with the ScopedLayers infrastructure the tools registry established: a
registration files into its calling context's layer (repository plugins and
host rows land global, a preset's skill-local lands in that preset's layer),
and a read merges the global layer with the viewing scope's chain, the
nearest layer winning duplicate names outright while rank keeps deciding
duplicates within one layer.

The web-app bundle re-enables the base skill registry row (skill-local and
tool-skill stay preset-owned), the standard preset drops its isolate skills
realm for bare rows over the host registry, tool-skill passes the calling
agent as the view scope, and the gateway's skills domain reads the host
registry in the presenter scope — a cold session now resolves its recorded
preset's standing key instead of failing.

docs/module-graph.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write docs/module-graph.md
-module-graph.md: e976945dffc6ad87cbc6e052790c54b14818ffe9
-module-graph.zh.md: 85485309846fe9442e377520afb6d740ee95c2be
+module-graph.md: 0488f68fa6acd2c0618690504de33768d9f64781
+module-graph.zh.md: 8508d5b47d70568fa6978d24ce6bab7dcb31d63f

docs/module-graph.md

@@ -382,6 +382,7 @@ flowchart TD
   pkg_system_prompt --> pkg_scope
   pkg_skill --> pkg_invariants
   pkg_skill --> pkg_llm
+  pkg_skill --> pkg_scope
   pkg_web --> pkg_invariants
   pkg_web --> pkg_llm
   pkg_api_gateway --> pkg_client_connection
@@ -1241,7 +1242,7 @@ flowchart TD
 | [`llm-pi-ai`](../packages/llm/llm-pi-ai) | `llm` | [`credentials`](../packages/credentials/credentials), [`environment`](../packages/util/environment), [`invariants`](../packages/support/invariants), [`llm`](../packages/llm/llm), [`settings`](../packages/settings/settings), [`timeout`](../packages/util/timeout) |
 | [`session`](../packages/core/session) | `core` | [`brand`](../packages/util/brand), [`invariants`](../packages/support/invariants), [`llm`](../packages/llm/llm), [`scope`](../packages/core/scope), [`type-meta`](../packages/typert/type-meta) |
 | [`system-prompt`](../packages/core/system-prompt) | `core` | [`invariants`](../packages/support/invariants), [`llm`](../packages/llm/llm), [`scope`](../packages/core/scope) |
-| [`skill`](../packages/skill/skill) | `skill` | [`invariants`](../packages/support/invariants), [`llm`](../packages/llm/llm) |
+| [`skill`](../packages/skill/skill) | `skill` | [`invariants`](../packages/support/invariants), [`llm`](../packages/llm/llm), [`scope`](../packages/core/scope) |
 | [`web`](../packages/web/web) | `web` | [`invariants`](../packages/support/invariants), [`llm`](../packages/llm/llm) |
 | [`api-gateway`](../packages/api/gateway) | `api` | [`client-connection`](../packages/client/connection), [`invariants`](../packages/support/invariants), [`typert-registry`](../packages/typert/registry) |
 | [`client-locale`](../packages/client/locale) | `client` | [`client-runtime`](../packages/client/runtime), [`client-ui-primitives`](../packages/client/ui-primitives), [`client-ui-slots`](../packages/client/ui-slots), [`invariants`](../packages/support/invariants) |

docs/module-graph.zh.md

@@ -384,6 +384,7 @@ flowchart TD
   pkg_system_prompt --> pkg_scope
   pkg_skill --> pkg_invariants
   pkg_skill --> pkg_llm
+  pkg_skill --> pkg_scope
   pkg_web --> pkg_invariants
   pkg_web --> pkg_llm
   pkg_api_gateway --> pkg_client_connection
@@ -1195,7 +1196,7 @@ flowchart TD
   pkg_acp_demo --> pkg_workspace_context
 ```
 
-| 包 | 分组 | 依赖项 |
+| Package | Group | Depends on |
 | --- | --- | --- |
 | [`invariants`](../packages/support/invariants) | `support` | — |
 | [`atomic-write`](../packages/util/atomic-write) | `util` | [`invariants`](../packages/support/invariants) |
@@ -1243,7 +1244,7 @@ flowchart TD
 | [`llm-pi-ai`](../packages/llm/llm-pi-ai) | `llm` | [`credentials`](../packages/credentials/credentials), [`environment`](../packages/util/environment), [`invariants`](../packages/support/invariants), [`llm`](../packages/llm/llm), [`settings`](../packages/settings/settings), [`timeout`](../packages/util/timeout) |
 | [`session`](../packages/core/session) | `core` | [`brand`](../packages/util/brand), [`invariants`](../packages/support/invariants), [`llm`](../packages/llm/llm), [`scope`](../packages/core/scope), [`type-meta`](../packages/typert/type-meta) |
 | [`system-prompt`](../packages/core/system-prompt) | `core` | [`invariants`](../packages/support/invariants), [`llm`](../packages/llm/llm), [`scope`](../packages/core/scope) |
-| [`skill`](../packages/skill/skill) | `skill` | [`invariants`](../packages/support/invariants), [`llm`](../packages/llm/llm) |
+| [`skill`](../packages/skill/skill) | `skill` | [`invariants`](../packages/support/invariants), [`llm`](../packages/llm/llm), [`scope`](../packages/core/scope) |
 | [`web`](../packages/web/web) | `web` | [`invariants`](../packages/support/invariants), [`llm`](../packages/llm/llm) |
 | [`api-gateway`](../packages/api/gateway) | `api` | [`client-connection`](../packages/client/connection), [`invariants`](../packages/support/invariants), [`typert-registry`](../packages/typert/registry) |
 | [`client-locale`](../packages/client/locale) | `client` | [`client-runtime`](../packages/client/runtime), [`client-ui-primitives`](../packages/client/ui-primitives), [`client-ui-slots`](../packages/client/ui-slots), [`invariants`](../packages/support/invariants) |