fix(mcp): send every repo search to code_search in the server instructions

[wongk]

Why

#35 made the "search with code_search" rule firmer in integrations/agents/shared/tool-discipline.md. It never reached Claude Code.

scripts/sync_agent_context.py deliberately gives Claude personas only a one-line tool rule (_CLAUDE_TOOL_DISCIPLINE), because Claude Code gets the full tool discipline from the MCP server's instructions field, SERVER_INSTRUCTIONS. Claude Code's lemoncrow:code build agents and main sessions are exactly the population the audit measured:

• Opus 5.5 build agents used code search for 3% of repo searches.
• Opus 5 build agents used it for 12%.
• Opus 5.5 build agents ran 22 shell repo searches per 100 tool calls.

#35 left all of them with the old wording. I claimed otherwise in #35's description without checking the generated Claude files.

Change

SERVER_INSTRUCTIONS gets the same rule #35 gave the other hosts:

• "Any repo search (symbols, strings, regex) → code_search, all terms in ONE call" replaces "Lead with code_search… never shell-grep or re-verify indexed results". Opus 5.5 read the old wording as covering only results already indexed.
• The bash bullet now names the commands: never grep -r/rg/git grep/find on the repo.

SERVER_INSTRUCTIONS was already at its 215-token ceiling. It stays at exactly 215, because the new wording replaces two things:

• the description of what a code_search call returns, which the tool's own schema already carries;
• the "re-verify" clause, which "inline source = already read" still covers.

This string ships to every host that renders MCP instructions. Codex and OpenCode ignore it; they already got the rule through #35's persona text.

Checked

• test_telegraphic_budget.py passes; the instructions are 215 of 215 tokens.
• 511 gateway and integration tests that exercise initialize or the instructions pass.
• Nothing else in the repo copies the old wording.
• ruff and black are clean.

Follow-up

Once this is installed, rerun the transcript audit and compare Opus 5.5's share of repo searches against the 3% baseline.