feat(prompts): revamp preset prompts, tool naming, and prompt templating

Rewrite the default/creative/strict presets (classic + agentic) into
structured sections: grounding and cite-by-title guidance, insufficient-
context behavior, current date, respond-in-user-language, scoped mermaid
usage, an untrusted-content guardrail, and a conditional XML-tagged
document context block. A memory directory listing is injected at render
time via the template prefetch mechanism so the model starts oriented
without burning a tool call.

Fixes along the way:
- Agentic preset swap was dead code: _get_prompt_content cached the
  classic preset before create_agent's swap check ran, so agentic and
  research agents always got the classic preset. The swap now happens
  inside _get_prompt_content.
- Jinja autoescape corrupted document content in custom prompts
  (< -> &lt;); prompts are not HTML, autoescape is now off.
- Literal {summaries} leaked into the prompt when no docs were
  retrieved; the placeholder is now stripped.
- Agentic/research prompts referenced tool names from a dropped naming
  scheme (search_internal, reason_think); they now reference the real
  names (search, reason).
- The strict preset told the model to "be very creative and use your
  imagination" right after "never make up information".
- extract_tool_usages recorded intermediate attribute chains as
  bare-tool usages, which meant "run all actions" at prefetch; only
  maximal chains are recorded now.
- Headless runs retrieved docs but never rendered them into the
  prompt; the prompt is now rendered like the streaming path.
- Default tools were unreachable by name in prompt templates
  (prefetch results were keyed by synthetic id only); defaults now
  claim the name key unless an explicit row shadows it.

Tool layer: memory/notes/todo actions are namespaced (memory_view,
note_overwrite, todo_create, ...) with legacy unprefixed names still
accepted via prefix stripping; duplicate action names across tools are
disambiguated with the owning tool's name instead of numeric suffixes;
thin tool descriptions rewritten (brave, duckduckgo, telegram, ntfy,
cryptoprice, read_webpage, internal_search, think).

Docs are now wrapped per chunk in <document index>/<source>/<content>
tags for citation-by-title support.

tests/test_coverage_gaps.py

@@ -611,11 +611,11 @@ class TestNotesToolEdgeCases:
     def test_get_actions_metadata(self, notes_tool):
         meta = notes_tool.get_actions_metadata()
         names = {a["name"] for a in meta}
-        assert "view" in names
-        assert "overwrite" in names
-        assert "str_replace" in names
-        assert "insert" in names
-        assert "delete" in names
+        assert "note_view" in names
+        assert "note_overwrite" in names
+        assert "note_str_replace" in names
+        assert "note_insert" in names
+        assert "note_delete" in names
 
     def test_get_config_requirements(self, notes_tool):
         assert notes_tool.get_config_requirements() == {}