Publish the agent skill that drives this CLI

`skills/remove-ai-watermarks/` teaches a coding agent to drive the CLI on
content the user generated, and refuses stock-agency and other third-party
paid-asset marks. It ships with this repository rather than as a fifth release
surface, and installs through `npx skills add` in any harness or as a Claude
plugin from `.claude-plugin/marketplace.json`.

`scripts/probe.py` measures capability rather than presence: a found binary said
nothing about whether the build can run a visible-mark command, so it writes a
blank PNG with zlib and struct and runs the installed `visible` and `invisible`
on it. Exit 2 is a state only a working stack reaches, and `invisible` checks
its extra before detection, so a signal-free image answers in 0.23s with no
model download. That distinction matters: without CUDA, `all` writes nothing
with the invisible extra installed and writes a useful visible+metadata result
without it, and both exit 1.

The skill also carries what a weak model gets wrong. It must report only what a
command in the session actually did, because a run on a machine with no pixel
stack produced a finished-looking removal report, complete with a size table for
a file nobody wrote. It must not read exit 2 as a verdict, because Click's usage
errors share that code. And it must get explicit consent before
`verify-openai-synthid`, which uploads the user's image to a third party.

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

docs/development.md

@@ -14,6 +14,10 @@ Read this reference for environment setup, dependency recovery, CI behavior, and
 - On an unreliable connection, sync `dev` plus only the required feature extras, such as `diffusion`, and run the checks directly instead of downloading every optional learned backend.
 - Run `uv` from the repository root or it may create a bare environment without the project dependencies.
 
+`maintain.sh` starts with `uv sync --all-extras`, so a lean environment is replaced whenever the gate runs. Syncing back down can leave `opencv-python-headless` half-removed: `import cv2` then succeeds against an empty namespace while `cv2.INTER_LINEAR` is gone, which surfaces as a suite that stalls or reports hundreds of unrelated failures. Repair it with `uv sync --frozen --extra dev --reinstall-package opencv-python-headless` rather than re-reading the diff.
+
+Pyright is only meaningful with the extras its imports need. Scoped to `src/`, a lean environment reports `TrustMark`, `transformers` and `huggingface_hub` as unresolved, which reads as a type error and is not one; add `--extra trustmark --extra classify` before believing it.
+
 The optional TrustMark decoder downloads weights into its installed package directory. After pruning that extra, a leftover weights directory can make availability checks see an empty namespace package. If Pyright reports an unknown `TrustMark` import and `find_spec("trustmark")` returns a loader-less spec, remove that regenerable remnant from the active virtual environment and resync.
 
 ### Known security-gate blocks