feat: add web UI prompt library from canonical workflows (#428)

Surface short copy/paste operator prompts derived from canonical workflow
files with workflow path and SHA-256 citations. Adds /prompts, /prompts/{id},
and /api/prompts with one-click copy.

Closes #428

webui/prompt_views.py

@@ -4,6 +4,7 @@ from __future__ import annotations
 
 import html
 
+from webui.layout import render_page
 from webui.prompt_library import PromptEntry, load_prompt_library
 
 
@@ -11,23 +12,6 @@ def _escape(text: str) -> str:
     return html.escape(text, quote=True)
 
 
-def render_prompts_page() -> str:
-    entries = load_prompt_library()
-    cards: list[str] = []
-    for entry in entries:
-        cards.append(_render_prompt_card(entry))
-    body = (
-        "<h2>Prompt library</h2>"
-        "<p>Short copy/paste task prompts derived from canonical workflows. "
-        "Full policy remains in the cited workflow files — not duplicated here.</p>"
-        f"{''.join(cards)}"
-        f"{PROMPT_PAGE_SCRIPT}"
-    )
-    from webui.layout import render_page
-
-    return render_page(title="Prompts", body_html=body)
-
-
 def _render_prompt_card(entry: PromptEntry) -> str:
     hash_short = (
         f"<code>{_escape(entry.workflow_hash[:12])}</code>"
@@ -77,4 +61,27 @@ document.querySelectorAll('.copy-btn').forEach((btn) => {
   });
 });
 </script>
-"""
+"""
+
+
+def render_prompts_page() -> str:
+    entries = load_prompt_library()
+    cards = "".join(_render_prompt_card(entry) for entry in entries)
+    body = (
+        "<h2>Prompt library</h2>"
+        "<p>Short copy/paste task prompts derived from canonical workflows. "
+        "Full policy remains in the cited workflow files — not duplicated here.</p>"
+        f"{cards}"
+        "<p><a href=\"/api/prompts\">JSON API</a></p>"
+        f"{PROMPT_PAGE_SCRIPT}"
+    )
+    return render_page(title="Prompts", body_html=body)
+
+
+def render_prompt_detail(entry: PromptEntry) -> str:
+    body = (
+        f"<p><a href=\"/prompts\">← All prompts</a></p>"
+        f"{_render_prompt_card(entry)}"
+        f"{PROMPT_PAGE_SCRIPT}"
+    )
+    return render_page(title=entry.label, body_html=body)