fix(client-web): pin keyed WebRow in boot smoke, show empty-search feedback

- built-boot smoke asserts [data-variant=web][data-tool=web_search/fetch]
  (the keyed WebRow) instead of [data-web] (which WebBlock draws even on the
  GenericToolCard fallback, so a silent keyed-registration failure passed).
- WebBlock renders an explicit empty-state note when a search returns no
  answer and no sources, instead of a blank <ol>; the chat row does not
  surface the raw result content, so the backend's 'No results found.' was
  otherwise invisible.
- README (ui-conversation, ui-primitives) and the frontend Agent Note record
  the unknown-web-kind null arm, the details-panel flattened body, and the
  empty-search copy; pairings re-recorded.

packages/client/ui-primitives/README.md

@@ -14,7 +14,7 @@ Pure React atoms (zero cordis): StateDot, ic_ds_* icons, Button/Pill/Menu/Modal/
 
 ## Web retrieval
 
-`WebBlock` renders a completed web retrieval, one component for both kinds of the `web` render intent (discriminated by `kind`). A `search` shows an optional provider answer (through `MarkdownText`) above an ordered citation list: each source is a safe external link labelled by its title, or its hostname, falling back to the raw URL when the URL does not parse or has no hostname (a `file:`/`data:` URL) so a label is never blank; its snippet and publication date render below it. Only http(s) URLs become anchors (`target`/`rel` set) — the http(s) subset of the allowlist `MarkdownText` applies to untrusted links (it also permits `mailto:`, excluded here); any other URL renders as plain text. A long list caps at `maxSources` (default 16, the TerminalBlock split arithmetic) with a head/tail collapse; the collapsed tail keeps each source's original citation number via `<li value>`, and the expand control is a marker-less `<li>` so the `<ol>` stays valid HTML. A `fetch` shows a compact summary: the linked final URL and its HTTP status. Both mark a capped retrieval. Rationale: [the web result card note](../../../.agents/notes/implemented/feature/2026-07-30-web-result-card-frontend.md).
+`WebBlock` renders a completed web retrieval, one component for both kinds of the `web` render intent (discriminated by `kind`). A `search` shows an optional provider answer (through `MarkdownText`) above an ordered citation list: each source is a safe external link labelled by its title, or its hostname, falling back to the raw URL when the URL does not parse or has no hostname (a `file:`/`data:` URL) so a label is never blank; its snippet and publication date render below it. Only http(s) URLs become anchors (`target`/`rel` set) — the http(s) subset of the allowlist `MarkdownText` applies to untrusted links (it also permits `mailto:`, excluded here); any other URL renders as plain text. A long list caps at `maxSources` (default 16, the TerminalBlock split arithmetic) with a head/tail collapse; the collapsed tail keeps each source's original citation number via `<li value>`, and the expand control is a marker-less `<li>` so the `<ol>` stays valid HTML. When a search legitimately returns no answer and no sources, the card shows an explicit empty-state note rather than a blank `<ol>` (the chat row does not surface the raw result content). A `fetch` shows a compact summary: the linked final URL and its HTTP status. Both mark a capped retrieval. Rationale: [the web result card note](../../../.agents/notes/implemented/feature/2026-07-30-web-result-card-frontend.md).
 
 ## Model Experience
 
@@ -29,5 +29,5 @@ None; this package neither assembles nor sends a provider request.
 - **Glyph-level icons are redrawn approximations** — the fish logo (and the sparkle held by ui-conversation) come from font glyphs whose vector geometry is not exportable from the local design data; hand-authored recreations stand in until an exact export path exists.
 - **Pill and Input have no design source** — both atoms are self-defined; the sidebar search field and view-tab strip that resemble them are consumer-owned compositions, not these atoms.
 - **StateDot `Active` variant is a hidden placeholder in the design** — not implemented; the four shipped states (done/warning/ongoing/error) are the complete P-I surface.
-- **This package's user-facing copy is inline Chinese, not localized** — the atoms are zero-cordis and so cannot reach `ctx.locale`; `TerminalBlock`'s exit-code and signal pills, its copy and expand controls, `CodeBlock`'s copy control, and `WebBlock`'s source expand/collapse controls and its source-list and fetch truncation notes are all hardcoded. This matches the repo-wide state the locale package records (only the Settings surface is translated); extracting these into the `zh`/`en` dictionaries needs a localization channel for zero-cordis atoms and belongs to that repo-wide extraction.
+- **This package's user-facing copy is inline Chinese, not localized** — the atoms are zero-cordis and so cannot reach `ctx.locale`; `TerminalBlock`'s exit-code and signal pills, its copy and expand controls, `CodeBlock`'s copy control, and `WebBlock`'s source expand/collapse controls, its source-list and fetch truncation notes, and its empty-search note are all hardcoded. This matches the repo-wide state the locale package records (only the Settings surface is translated); extracting these into the `zh`/`en` dictionaries needs a localization channel for zero-cordis atoms and belongs to that repo-wide extraction.
 - **`TerminalBlock` is not a terminal emulator** — it renders settled or still-running command output, not an interactive session: SGR color and attributes are honored, and so are the in-line cursor movements a progress line uses — carriage return, backspace, erase-in-line, tab stops and character width. Absolute cursor positioning, screen clearing, and alternate-screen sequences are stripped. Basic-16 magenta and cyan have no token equivalent and stay literal rgb.