Verify every doc claim against the source and fix what drifted

Every code-referencing claim in the docs, the README and the rules files was
checked against src/, and each finding was re-derived independently before it
was applied. 35 held, 5 were false positives.

Two of them were code, not text. `InvisibleOptions` promises in its docstring to
mirror `InvisibleEngine`, and two defaults had silently stopped:
`max_resolution=None` reached `_target_size`'s `max_resolution > 0` and raised
`TypeError` on every library call that left the options alone, and
`cpu_offload=True` made a library run slower than the identical CLI run. Both are
fixed, and `TestInvisibleOptionsMirrorTheEngine` compares the two signatures
field by field rather than pinning the two values that happen to be known. A
companion assertion in `TestTargetSize` reads the engine's own declared default,
so a drift on the engine side -- which the mirror check alone would accept,
because both sides would still agree -- fails too.

The user-facing docs: README called `invisible` GPU-optional where it raises
without CUDA, and gave the image `metadata` command `video metadata`'s output
rule, promising the source survives a command that overwrites it. Yuanbao was
missing from the supported-mark list. `veo` was listed among the video policies
that require a run anchor, though its row sets no `anchor_iou`.
`known-limitations` called ControlNet the default profile and contradicted
itself ninety lines below. An unescaped pipe truncated the `hailuo` table row.
The `dev` extra, the CI shape, ffmpeg's role, the sdist boundary and the
strength-curve range were corrected, and `remove_all`/`remove_batch`, the pill
gate, `erase --keep-metadata` and `all`'s CUDA failure mode were documented.

Research notes that described removed modules, extras and flags in the present
tense now say so once in the page banner instead of sentence by sentence, which
covers the whole page rather than the lines that happened to be noticed, and one
fixture is referred to by role rather than by name.

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

tests/test_api.py

@@ -195,6 +195,32 @@ class TestRemoveVisibleOutputPath:
         assert out.exists()
 
 
+class TestInvisibleOptionsMirrorTheEngine:
+    """``InvisibleOptions`` forwards to ``InvisibleEngine`` and promises every default
+    mirrors it. Compare the signatures field by field rather than pinning the values we
+    happen to know about, so the next field added on one side and not the other fails
+    here. See the incident record in ``docs/module-internals.md``."""
+
+    def test_every_default_matches_the_engine(self):
+        import dataclasses
+        import inspect
+
+        from remove_ai_watermarks.invisible_engine import InvisibleEngine
+
+        engine = {
+            name: p.default
+            for method in (InvisibleEngine.__init__, InvisibleEngine.remove_watermark)
+            for name, p in inspect.signature(method).parameters.items()
+            if p.default is not inspect.Parameter.empty
+        }
+        # ``force`` is a pipeline decision made before the engine runs, so it has no
+        # engine counterpart; ``remove_watermark`` spells the controlnet knob out in full.
+        renamed = {"controlnet_scale": "controlnet_conditioning_scale"}
+        options = {f.name: f.default for f in dataclasses.fields(api.InvisibleOptions) if f.name != "force"}
+
+        assert options == {name: engine.get(renamed.get(name, name), "<not an engine parameter>") for name in options}
+
+
 class TestRemoveAllLibrary:
     """The three-stage pipeline is a library function, not CLI-only.