Initial commit: postcard v1

Phone photo -> composited postcard (canvas templates, stamp corner,
EXIF-aware date/location, self-hosted handwriting font) with a small
server for share links, day-context caption drafting off goonk's
day-summary API, and Nominatim reverse geocoding.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

README.md

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+# postcard
+
+Turn a phone photo into a sendable postcard. Upload a photo, it gets
+composited onto a vintage postcard template (border, stamp corner,
+handwriting-style caption) entirely in the browser, then either download
+it right away or upload it for a shareable link.
+
+The caption is auto-drafted by assembling real fragments of that day
+(git activity, what was playing, a note title) via `server/src/caption.js`
+— never a free-text model call — and stays editable. With no day-context
+source configured it falls back to a small set of generic postcard-voice
+lines.
+
+Structurally this is a copy of [`latent`](../latent)'s upload → transform
+→ deliver shape and server (`db.js`/`ids.js`/`cleanup.js`/`ratelimit.js`/
+`routes.js`), with the transform swapped for postcard compositing. See
+[PROPOSAL.md](PROPOSAL.md) for the original design writeup.
+
+## Two finishing paths off one editor
+
+1. **Instant** — composite, then download directly, entirely client-side.
+   Optionally generate a share link (explicit action, not automatic).
+2. **Send** — uploads the composited image to server storage, returns a
+   link immediately (no delayed-reveal gate — that's `latent`'s gimmick,
+   not this one's).
+
+## Running locally
+
+```
+npm install --prefix server
+npm start --prefix server
+```
+
+Then open http://localhost:3098. `server`'s `start`/`dev` scripts load
+`../.env` automatically via Node's `--env-file-if-exists` — copy
+`.env.example` to `.env` at the repo root and adjust. `DATA_DIR` defaults
+to `./server/data` (gitignored) for the SQLite db and image blobs.
+
+## Deploying
+
+`docker compose up` using the provided `docker-compose.yml` (copy
+`.env.example` to `.env` and adjust — `IMAGE`/`HOST_PORT` are only read by
+compose, the rest are passed through to the container).
+
+## Config
+
+All via env vars:
+
+- `TTL_HOURS` — link retention (default 72h; shorter than `latent`'s,
+  since a postcard link is meant to be opened once, not browsed later).
+- `MAX_UPLOAD_BYTES`, `RATE_LIMIT_PER_HOUR` — basic abuse limits; no
+  accounts or auth on any endpoint, the link itself is the credential.
+- `DAY_SUMMARY_URL` — optional, no code-level default (set it in `.env`).
+  If set, `GET {url}?date=YYYY-MM-DD` is expected to return
+  `{ git?, spotify?, note? }` fragments for that date. `.env` here points
+  it at `https://goonk.se/api/day-summary`, goonk's live endpoint
+  (confirmed returning `{ git, spotify? }` — no `note` field observed yet).
+  A response body containing an `error` key (goonk's shape for a
+  missing/malformed date) is treated the same as no summary. Left unset,
+  captions fall back to generic lines — no invented personal data.
+- `NOMINATIM_URL` — reverse-geocoding endpoint for the stamp corner's
+  location line (only queried when a photo has EXIF GPS). Defaults to the
+  public `nominatim.openstreetmap.org`; `server/src/geocode.js` throttles
+  to 1 req/sec and caches by rounded coordinate per that API's usage
+  policy. No API key needed.
+
+## Notable implementation details
+
+- EXIF is parsed client-side with no dependency (`exif.js`) — just enough
+  to read `DateTimeOriginal` and GPS lat/lon out of a JPEG. Parse
+  failures/missing tags fall back to upload date / no location stamp,
+  never invented data.
+- The caption's handwriting font is self-hosted (`fonts/caveat-latin.woff2`,
+  Caveat, SIL OFL — see `fonts/OFL.txt`), not loaded from
+  fonts.googleapis.com at runtime.
+- The upload card offers separate "take a photo" (camera capture) and
+  "choose from library" buttons rather than relying on the OS's file
+  picker to offer both — some mobile browsers skip the chooser and go
+  straight to the camera when `capture` is set on a single input.
+
+## Non-goals
+
+No accounts, no "your postcards" history, no delayed-reveal mechanic, no
+free-text LLM-generated captions, no collaborative/multi-recipient cards.