feat(opencode): cut plugin system and remote behavior feeds; add SessionContext assembly and Runner

- delete plugin machinery (loader, install, meta, hooks) and all trigger sites
- fold first-party provider auth into static registry (provider/hooks.ts)
- remove remote instruction URL fetch, skills remote puller, TUI plugin host
- add session/context.ts: single provenance-tagged context assembly point
- add session/runner.ts: admit/context/stream/tools loop with compaction policy
- relocate audit artifacts to audit/ (FORK-AUDIT, instruction docs as evidence)

packages/opencode/src/project/bootstrap.ts

@@ -1,5 +1,4 @@
 import { makeGlobalNode } from "@opencode-ai/core/effect/app-node"
-import { Plugin } from "../plugin"
 import { Format } from "../format"
 import { LSP } from "@/lsp/lsp"
 import { Snapshot } from "../snapshot"
@@ -23,7 +22,6 @@ const layer = Layer.effect(
     const config = yield* Config.Service
     const format = yield* Format.Service
     const lsp = yield* LSP.Service
-    const plugin = yield* Plugin.Service
     const project = yield* Project.Service
     const shareNext = yield* ShareNext.Service
     const snapshot = yield* Snapshot.Service
@@ -34,8 +32,6 @@ const layer = Layer.effect(
       yield* Effect.logInfo("bootstrapping", { directory: ctx.directory })
       // everything depends on config so eager load it for nice traces
       yield* config.get()
-      // Plugin can mutate config so it has to be initialized before anything else.
-      yield* plugin.init()
       // Each service self-manages its own slow work via Effect.forkScoped against
       // its per-instance state scope. We just await materialization here.
       yield* Effect.forEach(
@@ -52,7 +48,7 @@ const layer = Layer.effect(
 export const node = makeGlobalNode({
   service: Service,
   layer: layer,
-  deps: [Config.node, Format.node, LSP.node, Plugin.node, Project.node, ShareNext.node, Snapshot.node, Vcs.node],
+  deps: [Config.node, Format.node, LSP.node, Project.node, ShareNext.node, Snapshot.node, Vcs.node],
 })
 
 export * as InstanceBootstrap from "./bootstrap"