fix(hygiene): unbreak format:check — it was RED on main and inert in CI

Two independent defects, both found by running the gate honestly instead of
bypassing it:

1. packages/mosaic/framework/tools/orchestrator/README.md fails the repo's own
   prettier config (unaligned markdown table). It landed via MERGED PR #868
   (b79336a8). A merged commit that fails `pnpm format:check` means the CI format
   gate did not block it — the gate is INERT. This is the P-QUEUE-001 /
   P-CONFORMANCE-001 failure class ("gate-6 was inert fleet-wide") reproduced on
   main, and it is exactly what this remediation mission exists to eliminate.

2. .prettierignore did not exclude Python build/test artifacts, so any local venv
   drops ~2400 third-party files into format:check and makes the gate unpassable
   in a working checkout. Added **/venv, **/__pycache__, **/.mypy_cache,
   **/.pytest_cache, **/htmlcov — the same category as the existing
   node_modules/dist/.next entries. This narrows what the gate SCANS (generated
   trees), never what it ENFORCES over source.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

.prettierignore

@@ -4,6 +4,14 @@ pnpm-lock.yaml
 **/node_modules
 **/drizzle
 **/.next
+# Python build/test artifacts — same category as node_modules/dist/.next above.
+# Prettier must never scan generated trees; without these a local venv poisons
+# `pnpm format:check` with thousands of third-party files.
+**/venv
+**/__pycache__
+**/.mypy_cache
+**/.pytest_cache
+**/htmlcov
 .claude/
 docs/tess/TASKS.md
 docs/scratchpads/

packages/mosaic/framework/tools/orchestrator/README.md

@@ -5,7 +5,7 @@ session health, continuation, and board maintenance. See
 `framework/guides/ORCHESTRATOR-PROTOCOL.md` for the surrounding process.
 
 | Script               | Purpose                                                                                         |
-|--------|---------|
+| -------------------- | ----------------------------------------------------------------------------------------------- |
 | `mission-init.sh`    | Initialize a new orchestration mission (manifest, scratchpad, TASKS.md).                        |
 | `mission-status.sh`  | Show the mission progress dashboard.                                                            |
 | `session-run.sh`     | Generate continuation context and launch the target runtime.                                    |
@@ -35,16 +35,23 @@ always-current `##` sections) is pinned and never touched:
 
 ```markdown
 # MOS ORCHESTRATION BOARD — LIVE state
+
 > protocol blockquote … (pinned)
 
 ## 🟦 Curated always-current section (pinned)
+
 …
 
 <!-- BOARD-ROLL:START -->
+
 ### 2026-07-22 (mid²²) — newest tick, stays longest
+
 …
+
 ### 2026-07-20 (dawn) — oldest tick, rolled first
+
 …
+
 <!-- BOARD-ROLL:END -->
 ```