Rebrand to Proof of Work; multi-user 0.4 package with curated library sync

Repo cleanup
- Add top-level .gitignore (was missing; node_modules, .next, *.s9pk,
  image.tar, seed/data/*.db, log files, etc.) and a root README.
- Delete legacy start9/0.3.5/ package (StartOS 0.3.5 wrapper, no longer
  the deploy target).
- Delete start9-example-packaging/ (template from another project).
- Delete planning docs (START9_PACKAGING_LOG.md, VERSIONING.md,
  STARTOS_0.4_UPGRADE_PROMPT.md, ICON_FILES_INDEX.md, etc.) — info now
  lives in the deploy guide and code comments.
- Drop the standalone Dockerfile, docker-compose.yml, ICON_*, and dev
  log/build artifacts from the app dir.
- Drop the v0.1.0:18/19/20 version files (they belonged to the legacy
  workout-log package and don't apply to the new id).

Rename + new package
- Rename app dir workout-planner/ -> proof-of-work/.
- Rename StartOS package id workout-log -> proof-of-work; the new id
  makes this a brand new StartOS service (clean cutover from the old
  one rather than in-place upgrade).
- Reset version graph; v1.0.0:1 is the seeded cutover release. The
  Dockerfile bakes a one-time /data snapshot and docker_entrypoint.sh
  copies it into the new volume on truly-fresh first boot only (both
  /data/app.db missing AND /data/.seeded absent).
- Move start9/0.4-migration/ -> start9/0.4/; the old start9/0.4/ stub
  is gone.

Curated exercise library (multi-user-aware)
- proof-of-work/prisma/exercises.seed.json is the canonical library
  shipped to every install (164 exercises today, dumped from the live
  snapshot).
- proof-of-work/scripts/sync-library.cjs (npm run sync-library) refreshes
  the JSON from start9/0.4/seed/data/app.db after refresh_seed.sh.
- proof-of-work/prisma/seed.ts now reads from the JSON instead of a
  hardcoded 52-exercise array; runs at Docker build time to seed the
  fallback DB and on first boot for fresh installs.
- proof-of-work/prisma/ensureExerciseLibrary.cjs runs on every container
  boot (from docker_entrypoint.sh) and INSERT OR IGNOREs every library
  entry for every user, keyed on (userId, name). Library updates flow
  to existing installs on package upgrade; user-custom exercises
  (isCustom=true) and any colliding names are never overwritten;
  removed exercises stay on existing installs (additive-only).

Deploy guide (start9/0.4/DEPLOY_040.md)
- Rewritten end-to-end for the workout-log -> proof-of-work cutover:
  refresh_seed, sync-library, build, sideload, verify, rotate creds,
  stop the old service, then post-cutover cleanup release v1.0.0:2.

start9/0.4/seed/README.md

@@ -0,0 +1,59 @@
+# Seed snapshot
+
+This directory contains a one-time snapshot of `/data/` from the live
+StartOS 0.3.5 install of **Proof of Work** (`proof-of-work`). It is baked into
+the 0.4 Docker image so the first 0.4 boot comes up with your production data
+already in place.
+
+## Source
+
+| Field | Value |
+| --- | --- |
+| Source file | `proof-of-work-2026-04-21T14-36-53-332Z.db` (user-provided backup) |
+| Exported on | 2026-04-21T14:36:53Z |
+| Exported from | StartOS 0.3.5 (aarch64) running `proof-of-work` v0.1.0.17 |
+| SQLite integrity check | `ok` |
+
+## Row counts (at snapshot time)
+
+| Table | Rows |
+| --- | --- |
+| `User` | 1 (`admin@local`) |
+| `UserPreferences` | 1 |
+| `Session` | 9 |
+| `Exercise` | 164 |
+| `Workout` | 348 |
+| `SetLog` | 5720 |
+| `Equipment` | 0 |
+| `Program` / `ProgramWeek` / `ProgramDay` / `ProgramExercise` | 0 |
+| `ContentItem` / `ContentChunk` | 0 |
+| `AISuggestion` | 0 |
+
+## What the seed does
+
+On **first boot** of this 0.4 package, `docker_entrypoint.sh`:
+
+1. Creates `/data/` if missing.
+2. If `/data/app.db` does NOT exist AND `/data/.seeded` does NOT exist, copies
+   everything under `/app/seed/data/` into `/data/` and writes `/data/.seeded`
+   with a timestamp.
+3. Logs which branch it took to stderr (visible in the StartOS log viewer).
+
+On every subsequent boot, the seed copy is skipped and the live `/data/` is
+used as the sole source of truth.
+
+## When to refresh this snapshot
+
+You usually refresh the seed only if you rebuild the package **before** doing
+the first-time sideload on the 0.4 host. Once the 0.4 service is running,
+stop rebuilding with a seed — the next package release (v0.1.0:19) removes
+the seed step entirely so releases don't risk overwriting live data.
+
+To refresh before first-time sideload, from the repo root:
+
+```sh
+./start9/0.4/refresh_seed.sh embassy@embassy.local
+```
+
+This SCPs the live `/embassy-data/package-data/volumes/proof-of-work/data/main/`
+files back into `start9/0.4/seed/data/` and runs an integrity check.