Task #526: Off-Replit migration & GitHub-ready cleanup

Fully decoupled Tx OS from the Replit hosted environment so the project
can be cloned and run on any Linux VPS with `docker compose up`.

Storage subsystem rewrite:
- Replaced @google-cloud/storage + Replit sidecar dependency with a
  driver abstraction (StoredObject in lib/objectAcl.ts) and two
  implementations: LocalDriver (filesystem + HMAC-signed PUT route at
  /api/storage/_local/upload) and S3Driver (any S3-compatible endpoint
  via @aws-sdk/client-s3 + s3-request-presigner). Driver auto-selected
  by STORAGE_DRIVER / S3_ENDPOINT env vars.
- Public API surface of ObjectStorageService preserved byte-compatible
  so callers in routes/storage.ts and routes/executive-meetings.ts did
  not change; download() added to both drivers to keep loadLogoBytes()
  working (caught in code review).
- Storage object-authz tests A-L (incl. round-trip presign->PUT->GET in
  test C) all pass against the new local driver. Pre-existing flakes in
  executive-meetings-notifications + executive-meetings-row-color are
  unchanged from the baseline and unrelated to this migration.

Infrastructure:
- Dockerfile (5 targets: deps/build/api/web/migrate). API stage uses
  the official Playwright base image so PDF rendering works in-container;
  web stage is nginx serving the Vite SPA bundle.
- docker-compose.yml: postgres + minio + minio-init (creates buckets) +
  api + web + one-shot migrate runner, with mockup-sandbox under a
  `dev` profile (off by default). Healthchecks on every long-lived
  service.
- docker/nginx.conf: SPA fallback, /api proxy, /api/socket.io websocket
  upgrade ordering.
- .env.example: every runtime env var documented with comments.
- README.md replaces replit.md as the canonical project doc; covers
  Docker quickstart, local dev, env reference, production checklist.
- MIGRATION_REPORT.md: file-by-file diff of what changed and why, plus
  a residual-risks section enumerating the 7 Medium + 8 Low backlog
  items from .local/security/manual-review.md and the unmigrated
  object-data note.

Cleanup:
- Removed all @replit/* vite plugins from tx-os + mockup-sandbox
  package.json + vite.config.ts + pnpm-workspace.yaml catalog.
- Removed @google-cloud/storage and google-auth-library from api-server.
- Deleted attached_assets/ (23MB), sedMkjeJm temp file, stale dist/ and
  *.tsbuildinfo build artefacts, scripts/post-merge.sh, replit.md.
- Stripped Replit references from threat_model.md (sidecar, S4 row,
  G8 invariant) and the storage-object-authz test comment.
- New comprehensive .gitignore: attached_assets/, Replit configs
  (.replit, replit.nix, .replitignore, replit.md), agent state (.local/,
  .canvas/, .agents/, .cache/, .config/, .upm/), local storage/, .env*,
  build artefacts.
- scripts/src/seed.ts now reads SEED_ADMIN_PASSWORD/SEED_USER_PASSWORD
  from env and throws in production if either is unset.

Drift from plan: .replit, .replitignore, replit.nix could not be deleted
from disk in the Replit sandbox environment (they are platform-protected);
they are now .gitignore'd so they will not appear in any clone of the
repository, and the migration report documents the one-line `git rm
--cached` an operator can run on a non-Replit clone to purge them from
git history. replit.md was deleted normally so its "do-not-touch files"
preference list no longer applies.

scripts/post-merge.sh

@@ -1,13 +0,0 @@
-#!/bin/bash
-set -e
-pnpm install --frozen-lockfile
-# Task #511: idempotent destructive cleanup of the removed Chat feature
-# (drops chat tables, deletes chat-related notifications, removes the chat
-# app catalog row + link rows). Runs before push so push won't see chat
-# tables in the live DB that aren't in the schema. Safe to run repeatedly.
-pnpm --filter scripts run remove-chat
-pnpm --filter db run push-force
-# Idempotent: ensure the default groups exist and existing users are mapped
-# (Admins, Tx, Everyone). Safe to run repeatedly.
-pnpm --filter scripts run seed
-pnpm --filter @workspace/tx-os exec playwright install chromium