feat(skills): web-search — live web search via search_web tool (llm-web-proxy)

Policy skill: search ON by default (agent decides when fresh data is
needed), user can say «поищи» to force or «без поиска» to disable for
the rest of the session (conversational, like using-interns grant).

TDD: RED (no-skill subagent refuses, offers rustup/blog workarounds) →
GREEN (with skill: calls search_web, returns answer with [1] sources +
honest staleness caveat). Live-verified against real DeepSeek search.

Depends on pi-extension search_web (OpeItcLoc03/pi-extensions) +
llm-web-proxy modelPrefix support (victor/llm-web-proxy v0.1.6).
Design: .wiki/concepts/web-search-skill-design.md.

README.md

@@ -121,6 +121,7 @@ an explicit `adapted-from` marker in its frontmatter.
 | `command-index` | `author: ours` — just/Makefile command-index convention (standard targets, auto-doc; idea 3/18) |
 | `code-review` | `adapted-from: mattpocock/skills @ 84fdeffd` (MIT) — two-axis + Fowler baseline; output: caveman-review format |
 | `writing-skills` | `adapted-from: obra/superpowers @ 6.2.0` (MIT) — TDD-for-skills core + ideya 8 self-skill-authoring |
+| `web-search` | `author: ours` — search_web tool (pi-extension) + policy: when to search, «без поиска» session-off |
 | all other `skills/*` | `author: ours` |
 
 Adaptation policy: a clone is rewritten to our conventions (`.tasks/` boards,