Add zone_split_shape strategy

[isaac0804]

Idea

zone_split_shape is split_shape (LeadAndSupportTactic + ShadowAndMarkTactic) with the 4/1 possession split shifted one robot by the ball's third: with the ball in our own third, 3 attack / 2 defend (a build-out from the back keeps cover); without it and the ball in their final third, 2 attack / 3 defend (a robot stays up to win the ball back). Near-ties keep the previous split (sticky) via friendly_closer_to_ball. Might beat split_shape because its all-in 4/1 swings leave nobody covering a turnover in either end.

Result

Not a round-robin. --reuse missed all 253 matches (the cache's newest entries are from 2026-10-01 22:35; pickers.py and tournament_lib.py/analysis/ changed since, so every key moved), so I stopped it rather than replay 253 matches and played --pair matches instead (zone_split_shape as config_a, 65s, 0 stalls):

Opponent	Result
split_shape	2-0
counter_flow	1-0
tiki_taka	1-0
low_block	1-0
clear_danger	0-0

4-1-0, goals 5-0. Single deterministic matches, one side each: a screen, not a ranking.

Checks

• Full suite --headless: 12448 passed, 88 xfailed. Lint passes.
• Changes only strategy/zone_split_shape.py, its import line in kernel_strategy.py, tests/strategy/test_zone_split_shape.py, and docs/strategies.md (catalog row + pair-match table).

Round-robin (added 2026-10-03)

Full 23-config round-robin with zone_split_shape in (--strict, 65s, 253 matches, 0 stalls, replays/tournament_20261003_093209; --reuse missed because the cache was keyed on the release version, fixed in #140):

Rank	Strategy	W-D-L	GF-GA	Points per match
1	split_shape	11-8-3	14-4	1.86
2	counter_flow	9-13-0	9-0	1.82
3	clear_danger	10-10-2	10-2	1.82
4	zone_split_shape	10-8-4	14-7	1.73
5	give_and_go_solo	8-12-2	10-4	1.64

Below its parent split_shape (which beats it on points and concedes fewer), so the 4-1-0 from five pair matches above was optimistic. The pair-match table was moved out of docs/strategies.md into this description.

🤖 Generated with Claude Code

https://claude.ai/code/session_01SACGSprm9GiBueqKdxsy2j

[isaac0804]

Closing without merging: in the full 23-config round-robin zone_split_shape finished 4th (1.73 points per match), below its parent split_shape (1st, 1.86), so the idea doesn't improve on what it builds on. Kept as a record; the branch stays. This PR was also the first end-to-end trial of the strategy/* workflow, which worked.