Tighten tool surface consistency

Four passes of audit-and-patch on the tool surface, condensed.

Tool API shape:
- Todo tools collapse to a single list-based form (one arg per tool,
  always a list, no dual-mode validator). Result-field names line up
  across the family — created_count / updated_count / marked_count /
  deleted_count, and _mark returns a single "marked" key plus the new
  status instead of marked_done / marked_pending.
- list_notes splits the overloaded total_count into filtered_count
  (matches) and total_count (grand total), matching list_todos. All
  three notes mutations now echo total_count and note_id.
- finish_scan drops the machine-code error strings; a single human
  "error" key carries the reason on every failure path.
- scope_rules delete echoes a message so the renderer's success
  branch has something to surface.

Failure-key unification: every tool now uses {"success": False,
"error": "..."} on failure paths. Touched thinking, web_search,
reporting, and finish. Trailing periods on error strings swept clean
across the whole tool tree.

Tool prompts (docstring re-imports vs main):
- create_vulnerability_report re-imports the CWE reference catalog,
  multi-part fix rules, fix_before/fix_after PR-suggestion mechanics,
  the COMMON MISTAKES list, the informational-vs-actionable
  distinction, and file-path examples.
- web_search re-imports concrete example queries.
- list_sitemap docstring fixed hasDescendants -> has_descendants
  (the camelCase reference never matched our snake_case schema).
- create_agent.skills description "Comma-separated" -> "List of".
- factory.py module docstring no longer claims there's no runtime
  skill-loading tool. agents_graph module docstring lists stop_agent.
- system_prompt nudges loading the matching skill before guessing
  payloads or syntax from memory.

TUI:
- proxy_renderer was reading stale field names from the pre-SDK
  schema (requests / total_count / statusCode / matches /
  showing_lines); now reads entries / page_info / status_code / hits
  / page+total_lines. Three proxy operations were rendering empty
  before this.
- Idle-pane placeholder text trimmed to "Loading...".

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

strix/agents/factory.py

@@ -11,8 +11,9 @@ Two flavors:
   ``create_agent`` graph tool. Carries ``agent_finish`` and stops
   after that tool reports ``agent_completed``.
 
-Skills are baked into the system prompt at scan bring-up; there's no
-runtime skill-loading tool.
+Skills are baked into the system prompt at scan bring-up. The
+``load_skill`` tool is also available for on-demand inline reference
+to any skill the agent didn't preload.
 """
 
 from __future__ import annotations

strix/agents/prompts/system_prompt.jinja

@@ -149,6 +149,7 @@ OPERATIONAL PRINCIPLES:
 - Prefer established industry-standard tools already available in the sandbox before writing custom scripts
 - Do NOT reinvent the wheel with ad hoc Python or shell code when a suitable existing tool can do the job reliably
 - Skills relevant to your task are preloaded into this prompt at scan start; refer back to them when you need vulnerability-, protocol-, or tool-specific guidance
+- For skills not preloaded, use `load_skill` to pull them inline — prefer loading the matching skill before guessing payloads, workflows, or tool syntax from memory
 - Use custom Python or shell code when you want to dig deeper, automate custom workflows, batch operations, triage results, build target-specific validation, or do work that existing tools do not cover cleanly
 - Chain related weaknesses when needed to demonstrate real impact
 - Consider business logic and context in validation