fix(web-presenter): dim-Markdown web fallback, memoize fetch conversion, strip note residue

Route a `web` result card's raw-content fallback through the TUI's dim
Markdown path (render() only recognized `card: 'generic'` as markdown
content, so web fallback rendered as bare undimmed text).

Memoize renderFetchOutput per (result, maxOutputChars) so the registry's
twin output.render / output.presentationMeta calls on the same frozen
result run one HTML->markdown conversion instead of two.

Remove the trailing `</content>`/`</invoke>` protocol residue from both
sides of the web-result-card Agent Note and re-record the pairing.

.agents/notes/implemented/feature/2026-07-30-web-result-card.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 .agents/notes/implemented/feature/2026-07-30-web-result-card.md
-2026-07-30-web-result-card.md: da8fc8162e4e52b76162c50c751d31ef6a9c3b1d
-2026-07-30-web-result-card.zh.md: 286d9ed659dbea20858798723d9c040f551df0b3
+2026-07-30-web-result-card.md: 3c1f3e69e612d76b959af3304203dcc4ad125019
+2026-07-30-web-result-card.zh.md: e8a3f38d51f4dc81362f5090ff553cfaff21823c

.agents/notes/implemented/feature/2026-07-30-web-result-card.md

@@ -42,5 +42,3 @@ A future web tool that wants this card declares `presentResult` returning a `car
 
 - [Tagged render-intent union for tool-call presentation](../architecture/2026-07-02-tool-render-intent-union.md) — the `card`-tagged vocabulary this extends with the `web` arm.
 - [Web terminal card](2026-07-28-web-terminal-card.md) — the precedent that carried the bash `terminal` render intent to the browser; the web frontend consumer of this arm is its analogue, deferred to a later PR.
-</content>
-</invoke>

.agents/notes/implemented/feature/2026-07-30-web-result-card.zh.md

@@ -42,4 +42,3 @@ web 前端消费者是一个独立的后续 PR：本 PR 新增契约分支并让
 
 - [标签化的工具调用渲染意图联合类型](../architecture/2026-07-02-tool-render-intent-union.md) —— 本卡片以 `web` 分支扩展的 `card` 标签词汇表。
 - [Web terminal card](2026-07-28-web-terminal-card.md) —— 把 bash `terminal` 渲染意图带到浏览器的先例；本分支的 web 前端消费者是它的对应物，推迟到后续 PR。
-</content>