Extract `content-lane/*` as one vertical slice

[JSONbored]

Problem: The content-lane subtree (the curated-list rule engine) is explicitly self-documented as a leaf module with almost no cross-cutting imports into the rest of the review logic — the cleanest possible extraction boundary in the whole review/ tree, and a good place to validate the shim pattern on a genuinely new (not already-twinned) slice before touching anything more central.

Area: ORB / gittensory-engine

Proposal: Move the entire content-lane subtree into gittensory-engine as a self-contained unit, with a thin adapter file remaining in src/ to wrap it for the Worker.

Deliverables:

• The content-lane subtree moved, with a working adapter shim.

Acceptance criteria:

• All content-lane behavior is unchanged end-to-end after the move.
• The adapter file's import paths are confirmed correct and the visual-capture dependency it has on an I/O-bound sibling module still resolves correctly.

[linear-code]

JSO-3540