conductor(tier-setup): MANDATORY pre-action reading + pre-commit abort on leak

ROOT CAUSE (post-mortem at docs/reports/TIER2_MCP_REGRESSION_20260624.md):
- Tier 1 asserted claims from old reports without re-verifying (SSDL campaign
  was designed from a static text string '6 nil-check functions' in
  src/code_path_audit_gen.py:108 that was never a runtime measurement)
- Tier 2 (autonomous) made an empty fix commit (2b7e2de1) for the MCP
  regression; the pre-commit hook silently stripped opencode.json +
  mcp_paths.toml and the agent reported success without verifying with
  'git show HEAD --stat'
- Both happened because neither tier read the critical files before acting

THE FIX (this commit):

1. .agents/agents/tier1-orchestrator.md: add MANDATORY pre-action reading
   list (6 files: AGENTS.md, conductor/workflow.md, current track spec/plan,
   the 3 code_styleguides). Reference the 2026-06-24 SSDL failures.

2. .agents/agents/tier2-tech-lead.md: add MANDATORY pre-action reading list
   (8 files: AGENTS.md, workflow.md, edit_workflow.md, the githooks
   forbidden-files.txt, the tier2_leak_prevention spec, the 3 styleguides)
   + the MANDATORY pre-commit verification gate (3 checks per commit).

3. .agents/agents/tier3-worker.md: add 4-file read list (AGENTS.md, task
   spec, relevant styleguide, the actual code being modified). Tier 3 doesn't
   need the full 8-file list — Tier 2's task spec is the contract.

4. .agents/agents/tier4-qa.md: same 4-file read list (analysis context).

5. conductor/tier2/agents/tier2-autonomous.md: add the 8-file MANDATORY
   pre-action reading list + the MANDATORY pre-commit verification gate.

6. conductor/tier2/commands/tier-2-auto-execute.md: add the 8-file list
   to the pre-flight section (step 0).

7. conductor/tier2/githooks/pre-commit: change behavior from 'silent strip
   + commit anyway' to 'strip + ABORT commit with diagnostic message'.
   The previous behavior led to empty commits (the 2026-06-24 regression).
   The agent MUST investigate the leak before retrying the commit.

ENFORCEMENT (all tiers):
- First commit of any track must include 'TIER-N READ <list> before <task>'
  in the commit message. The failcount contract treats an unacknowledged
  first commit as a red-phase failure (per the error_handling.md Rule #0
  precedent).

NOT IN THIS COMMIT (deferred to followup tracks per the post-mortem):
- Rule 4 (CI gate for required files via scripts/audit_branch_required_files.py)
- AGENTS.md addition of the canonical 'MANDATORY Pre-Action Reading' section
  (separate track to ensure the project-root rules reflect the same list)
- Cross-platform agent files (.opencode/, .claude/, .gemini/) — those are
  generated from the canonical .agents/agents/ files; this commit updates
  the canonical sources.

7 files modified, 109 insertions, 6 deletions.

.agents/agents/tier4-qa.md

@@ -27,3 +27,13 @@ Your goal is to analyze errors, summarize logs, or verify tests.
 You have access to tools for reading files, exploring the codebase, and web tools.
 You CAN execute PowerShell scripts or run shell commands via discovered_tool_run_powershell for diagnostics.
 ONLY output the requested analysis. No pleasantries.
+
+## MANDATORY: Pre-Action Required Reading (added 2026-06-24)
+
+Before any analysis, the agent MUST read:
+1. `AGENTS.md` (project root) — operating rules
+2. The task spec (provided by Tier 2) — what to analyze
+3. The relevant `conductor/code_styleguides/*.md` (for context on the convention being audited)
+4. The actual code/logs being analyzed (use `py_get_definition` + `read_file` with `start_line`/`end_line`)
+
+**Enforcement:** Tier 4 workers do NOT need the full 8-file list. The 4 files above are sufficient for analysis.