Fix Launch Octopus co-op interactions and charged-shot graphics

[mstan]

Co-op players can miss Gulpfer captures and the Launch Octopus vortex, and a partner riding charged Shotgun Ice can remain in a falling animation. Simultaneous native charged busters also share graphics incorrectly.

• Keep each fish's captured player through hold, escape and release; free fish skip players already captured elsewhere. Returned players remain eligible, and older captured saves recover ownership.
• Apply the vortex's pull and lift to both living bodies while advancing the effect once.
• Preserve the ice sled's new landing flag during the partner contact pass.
• Include X's native charge without the arm upgrade in the existing graphics isolation and preserve the tile retained by the short bottom-row upload.

Validation: focused ROM checks passed for both character assignments, returned players, separate captures and release, both world actors, vortex entry/exit, ice sled standing/carry, simultaneous charged shots, and deterministic snapshot replay. Fish and vortex cases also passed with independent cameras enabled without network sessions. The synthetic projectile fixture was checked in unified mode; independent views can cull that imposed placement. The Windows Release build succeeds.

The harness uses privately supplied slot 04 and slot 07 saves and extracted source assets. Invocation and native routine details are documented in docs/coop-port.md.