docs(workflow,agents): remove 'large files are bad' propaganda; add naming rule

The user called out the LLM training data bias: 'small files are
good, large files are bad.' This is wrong for production codebases.
Unreal has 15K+ line files; OS kernels, game engines, compilers all
routinely have 10K+ line files. File size is a non-issue. Cognitive
load is managed via naming, regions, and navigation tools (the
manual-slop MCP) — NOT via file splitting.

Updates:

1. AGENTS.md (master agent guidance):
   - Added 'File Size and Naming Convention' section
   - Added the hard rule: 'New namespaced src/<thing>.py files may
     only be created on the user's explicit request. If you find
     yourself about to create one, ASK FIRST.'
   - Defaults: helpers and sub-systems go in the parent module

2. conductor/workflow.md (Guiding Principles):
   - Removed 'Do NOT perform large file writes directamente' from
     principle 7 (it was a delegating rule, but 'large file writes'
     carried the propaganda)
   - Added principle 8: 'File Naming Convention (HARD RULE)' that
     references AGENTS.md
   - Re-phrased principle 9 (Research-First) to clarify it's about
     navigation efficiency, not file size

3. conductor/code_styleguides/python.md:
   - Removed the 'extremely large files that violate the Anti-OOP
     rule by necessity' framing
   - Added the new rule about new src/<thing>.py files

4. .opencode/agents/tier3-worker.md and .opencode/agents/tier4-qa.md:
   - Re-phrased 'Do NOT read full large files' to 'Use skeleton
     tools to navigate any file regardless of size. File size is
     not a concern; the right tools are.'
   - Added the new rule about not creating new src/<thing>.py
     files unless user explicitly requests it

5. conductor/tracks/qwen_llama_grok_followup_20260611/plan.md:
   - Updated the 'Naming Convention' section to reference the new
     'user explicit request' rule

This is docs-only. No code changes. The rule is now codified:
agents must ASK FIRST before creating new top-level src/ files.

.opencode/agents/tier3-worker.md

@@ -151,9 +151,10 @@ Examples of BLOCKED conditions:
 ## Anti-Patterns (Avoid)
 
 - Do NOT use native `edit` tool - use MCP tools
-- Do NOT read full large files - use skeleton tools first
+- Use skeleton tools (manual-slop-py-get-skeleton, manual-slop-py-get-code-outline, manual-slop-get-file-slice) to navigate any file regardless of size. File size is not a concern; the right tools are.
 - Do NOT add comments unless requested
 - Do NOT modify files outside the specified scope
+- Do NOT create new `src/*.py` files unless the user explicitly requests it. Helpers go in their parent module (e.g., AI-client code goes in `src/ai_client.py`, not new `src/ai_client_<thing>.py`). If you find yourself about to create a new `src/<thing>.py` file, ASK FIRST. See `AGENTS.md` "File Size and Naming Convention" for the full rule.
 - DO NOT SKIP A TEST IN PYTEST JUST BECAUSE ITS BROKEN AND HAS NO TRIVIAL SOLUTION OR FIX.
 - DO NOT SIMPLIFY A TEST JUST BECAUSE IT HAS NO TRIVIAL SOLUTION TO FIX.
 - DO NOT CREATE MOCK PATCHES TO PSEUDO API CALLS OR HOOKS BECAUSE THE APP SOURCE WAS CHANGED. ADAPT TESTS PROPERLY.

.opencode/agents/tier4-qa.md

@@ -138,7 +138,8 @@ If you cannot analyze the error:
 ## Anti-Patterns (Avoid)
 
 - Do NOT implement fixes - analysis only
-- Do NOT read full large files - use skeleton tools first
+- Use skeleton tools (manual-slop-py-get-skeleton, manual-slop-py-get-code-outline, manual-slop-get-file-slice) to navigate any file regardless of size. File size is not a concern; the right tools are.
+- Do NOT create new `src/*.py` files unless the user explicitly requests it. See `AGENTS.md` "File Size and Naming Convention" for the full rule.
 - DO NOT SKIP A TEST IN PYTEST JUST BECAUSE ITS BROKEN AND HAS NO TRIVIAL SOLUTION OR FIX.
 - DO NOT SIMPLIFY A TEST JUST BECAUSE IT HAS NO TRIVIAL SOLUTION TO FIX.
 - DO NOT CREATE MOCK PATCHES TO PSEUDO API CALLS OR HOOKS BECAUSE THE APP SOURCE WAS CHANGED. ADAPT TESTS PROPERLY.