fix(voice/consistency): vary stock formulas, vendor-balance orient.py, unify the loop

- Vary 11 instances of two boilerplate openers ("A generic X course…" /
  "Strip away X…") across 10 modules so they read as distinct, concrete prose;
  kept the few deliberate, voice-distinct uses; locked exemplars untouched.
- M23 orient.py: detect a vendor-balanced set of AI-instruction filenames
  (AGENTS.md/CLAUDE.md/GEMINI.md/.cursorrules/.cursor/rules/copilot-instructions)
  instead of singling out one vendor. Still runs.
- Render the collaboration loop consistently as seven stations
  (issue->branch->implementation->PR->review->merge->closed) in M25/M26 to match
  M11 and the syllabus.

Closes #48
Closes #49
Closes #51

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TfzV5QvtPDz8LJS3Pu5VLT

modules/23-working-with-existing-codebases/lab/orient.py

@@ -49,8 +49,14 @@ SIGNALS: dict[str, str] = {
     "README.md": "Has a README — read it first",
     "CONTRIBUTING.md": "Has contributor guidance — read before changing",
     "ARCHITECTURE.md": "Has an architecture doc — rare and valuable",
+    # Committed AI-instruction files. Name the real ones across vendors — singling out one
+    # would both miss files and cut against the vendor-neutral point (Module 5).
     "AGENTS.md": "Has a committed AI instructions file (Module 5)",
     "CLAUDE.md": "Has a committed AI instructions file (Module 5)",
+    "GEMINI.md": "Has a committed AI instructions file (Module 5)",
+    ".cursorrules": "Has a committed AI instructions file (Module 5)",
+    ".cursor/rules": "Has a committed AI instructions file (Module 5)",
+    ".github/copilot-instructions.md": "Has a committed AI instructions file (Module 5)",
 }
 
 # Common test-runner hints keyed off a present signal file.