v2.1.0: symlink OMOS bundled skills from image, bump opencode 1.17.4->1.17.5

Deploy the five oh-my-opencode-slim bundled skills (clonedeps, codemap,
deepwork, oh-my-opencode-slim, simplify) by symlinking them from the image
path into ~/.agents/skills/ on every container start, instead of the
installer copying them into the persistent config volume on first run only.
Image-sourced links mean 'docker compose pull' + recreate refreshes the
skills with no installer run and no config reset; the old copy-on-first-run
froze them in the volume forever.

- entrypoint-user.sh: new non-fatal OMOS bundled-skills reconcile block
  (runs after skillset deploy so OMOS wins the simplify collision; absolute
  symlinks; gated by OMOS_SKILLS, now independent of ENABLE_OMOS). Both
  installer calls now pass --skills=no. One-time migration backs up (never
  deletes) frozen real copies in ~/.config/opencode/skills/ to .bak.<epoch>.
- scripts/smoke-test.sh: assert the bundled-skills source path on omos.
- Bump OPENCODE_VERSION 1.17.4 -> 1.17.5.
- Versioning: document the move to independent image semver (v2.0.0 was the
  decouple point), mirroring pi-devbox. README/AGENTS/.env.example/CHANGELOG
  updated; new docs/omos-skills.md.

README.md

@@ -146,8 +146,8 @@ docker compose exec -u developer devbox aws --version
 | `EDITOR` | Default text editor | `nvim` |
 | `ENABLE_OMOS` | Enable oh-my-opencode-slim multi-agent orchestration | `false` |
 | `OMOS_TMUX` | Enable tmux pane integration for OMOS | `false` |
-| `OMOS_SKILLS` | Install OMOS recommended skills on first run | `true` |
-| `OMOS_RESET` | Force regenerate OMOS config on next start | `false` |
+| `OMOS_SKILLS` | Symlink bundled OMOS skills from the image into `~/.agents/skills/` each start | `true` |
+| `OMOS_RESET` | Force regenerate OMOS config on next start (does not affect skills) | `false` |
 | `SKILLSET_CONTAINER_PATH` | Path to skillset repo inside container (for auto-deploy when not at /workspace/skillset) | Auto-detect |
 
 ### Reaching your LAN from the container
@@ -207,7 +207,7 @@ Host my-remote
 
 ### Custom opencode config
 
-Opencode configuration is persisted automatically via the named volume `devbox-opencode-config`. This volume is mounted at `/home/developer/.config/opencode` by default — no host directory setup required. All changes to `opencode.jsonc`, skills, and (on the OMOS variant) `oh-my-opencode-slim.json` survive container recreation.
+Opencode configuration is persisted automatically via the named volume `devbox-opencode-config`. This volume is mounted at `/home/developer/.config/opencode` by default — no host directory setup required. Changes to `opencode.jsonc` and (on the OMOS variant) `oh-my-opencode-slim.json` survive container recreation. Auto-deployed skills are *not* stored here — skillset and OMOS skills are symlinked into `~/.agents/skills/` and rebuilt on every start (see [Custom skills](#custom-skills) and [docs/omos-skills.md](docs/omos-skills.md)).
 
 When an existing `opencode.jsonc` is found in the volume, the `OPENCODE_PROVIDER` auto-config is skipped.
 
@@ -232,6 +232,8 @@ When a skillset repo is detected, its skills are symlinked into `~/.agents/skill
 
 > **Warning:** Do not bind-mount a host `~/.agents/skills` directory directly into the container. This conflicts with the symlink-based auto-deploy mechanism and causes broken skill references.
 
+On the OMOS variant, the five skills bundled with oh-my-opencode-slim are also symlinked into `~/.agents/skills/` on each start — **from the image**, so pulling a newer image updates them with no installer run and no config reset. See [docs/omos-skills.md](docs/omos-skills.md).
+
 ### Neovim configuration
 
 The image includes neovim 0.12 with `EDITOR=nvim` set by default. To use your own neovim config (and have plugins auto-install via lazy.nvim on first start), mount it from the host:
@@ -457,7 +459,7 @@ ENABLE_OMOS=true
 docker compose run --rm devbox
 ```
 
-On first start, the entrypoint runs the oh-my-opencode-slim installer in non-interactive mode. It generates agent configuration at `~/.config/opencode/oh-my-opencode-slim.json` inside the container. The default preset uses OpenAI models — edit the generated config or mount your own to customize.
+On first start, the entrypoint runs the oh-my-opencode-slim installer in non-interactive mode. It generates agent configuration at `~/.config/opencode/oh-my-opencode-slim.json` inside the container. The default preset uses OpenAI models — edit the generated config or mount your own to customize. The installer no longer manages skills (`--skills=no`); the bundled skills are symlinked from the image on every start — see [docs/omos-skills.md](docs/omos-skills.md).
 
 ### OMOS Environment Variables
 
@@ -465,8 +467,8 @@ On first start, the entrypoint runs the oh-my-opencode-slim installer in non-int
 |---|---|---|
 | `ENABLE_OMOS` | `false` | Activate oh-my-opencode-slim on container start |
 | `OMOS_TMUX` | `false` | Enable tmux pane integration (tmux is included in the base image) |
-| `OMOS_SKILLS` | `true` | Install recommended skills (simplify, agent-browser, cartography) |
-| `OMOS_RESET` | `false` | Force regenerate config on next start (backs up existing config) |
+| `OMOS_SKILLS` | `true` | Symlink the bundled OMOS skills (`clonedeps`, `codemap`, `deepwork`, `oh-my-opencode-slim`, `simplify`) from the image into `~/.agents/skills/` on each start. Independent of `ENABLE_OMOS`. See [docs/omos-skills.md](docs/omos-skills.md) |
+| `OMOS_RESET` | `false` | Force regenerate config on next start (backs up existing config). Does **not** affect skills |
 
 ### Custom Configuration