fix: drop tool-web subpath exports, align with tool-bash single-entry shape

The web tool package exposed ./search and ./fetch as standalone subpath
plugins, but nothing consumed them, the RFC never called for them, and the
sibling dsh-tool-bash (also a multi-tool consumer) ships a single entry and
selects tools via config. The extra entries also tripped the workspace
constraints gate, whose expected `files` list covers single-entry and bin
packages but not a non-bin multi-entry one.

Collapse to a single `.` entry: drop the ./search|./fetch exports and their
lib/*.js from package.json files, delete the per-package tsdown override (the
root config's lib/types/index.js entry now suffices), and remove the
plugin-shaped name/inject exports from search.ts/fetch.ts (renaming each
apply to its applyWeb{Search,Fetch}Tool helper, still composed by the root
plugin and re-exported from the index). Selective enablement stays via the
existing { search?, fetch? } config. Docs updated to match.

packages/web/tool-web/README.md

@@ -2,7 +2,7 @@
 
 The model-facing web tool suite — `web_search` and `web_fetch` — over the [web capability seam](../web/README.md) (`ctx.web`). It owns model-facing concerns only: tool names, JSON schemas, snake_case argument names, prompt sections, the result-count bound, result formatting, HTML→markdown presentation, and `presentCall`. All web access goes through `ctx.web`; this package never imports a concrete provider.
 
-Each tool is also a subpath plugin (`@deepseek-ai/dsh-tool-web/search`, `/fetch`) for focused deployments.
+Each tool is registered independently; a product that wants only one disables the other via config (`{ search: false }` / `{ fetch: false }`).
 
 ## Tools