instagram-logger — Phase 3 vertical slice

Self-hosted archiver for a single Instagram account's saved posts. This commit ships the smallest end-to-end demo described in .omc/plans/plan.md §9: a CLI login, a one-shot first-page ingest, a localhost-only API with full Range / If-None-Match support on media, and a 3-column React grid.

Quick start

# 1. Install backend + frontend deps (uses a local .venv and npm).
just install

# 2. Log in to Instagram once. Prompts for username/password and 2FA if challenged.
#    Writes data/instagrapi_settings.json.
just login

# 3. Pull the first page of "All Posts" (does HTTP + media downloads).
just sync

# 4. Run the API on http://127.0.0.1:8000 (migrations apply at startup).
just dev

# 5. In another terminal, run the frontend dev server.
cd frontend && npm run dev
# Open http://localhost:5173

What the slice covers

• python -m backend.ig_client.login — interactive login, settings persist.
• python -m backend.ingest --first-page-only — first page of "All Posts", per-post BEGIN IMMEDIATE transactions, atomic media writes (verified Content-Length + fsync + rename), sha256 path layout under data/media/<aa>/.
• uvicorn backend.main:app — 127.0.0.1 only (refuses non-loopback unless ALLOW_REMOTE=1). Endpoints: GET /api/posts, GET /api/media/:sha256 (full Range + 304), GET /api/auth/status.
• React grid at /: grid grid-cols-3 gap-1 of <img src="/api/media/:sha256">.

What it does NOT do yet

Collections enumeration, post detail modal, search/filters, scheduler, 2FA banner UI, launchd plist — see .omc/plans/plan.md §10 batches B1-B6.