docs(core): snapcompact audit — measured shape/recall table, frank-archon image-count budget, 85% trigger law

Live probe against frank-archon (212,916-char archive, 8 planted facts):
auto shape 8on22-bw reads back 8/8 recall at 47% of raw-text billed
tokens; both denser grids drop characters. Lands the docs for the paired
live-config changes (thresholdPercent 95->85, imageCountBudget 16) and
records the catalog-only frame-pricing law (radiance ~2,400 tok/frame vs
the harness's blind 5,024 floor).

Refs #81

omp-docs/core/index.md

@@ -16,5 +16,6 @@ These files define the structural conventions that govern the agent system itsel
 * [OMP Status Line Customization](statusline.md) — How presets, composer shapes, and segment arrays actually interact; the fleet's tuned bar. (moved from /pi/, 2026-10-19)
 * [OMP Subagent Limits & Fan-out Policy](subagent-limits.md) — Live caps: concurrency 2, no nested spawns (the `maxRecursionDepth: 0` trap), per-endpoint in-flight ceilings, isolation policy. (moved from /pi/, 2026-10-19)
 * [WAN Model Access](wan-model-access.md) — Driving the fleet's models from outside the home network through the OpenWebUI door: the command, the key file and its rotation law, what the door publishes, and the off-network failure modes.
+* [OMP Snapcompact — Bitmap-Frame Compaction](snapcompact.md) — What shape frank-archon actually reads, the measured recall/billing table, the `imageCountBudget` knob and the pricing that isn't, and the 85 % trigger law.
 
 **Change log:** the bundle keeps exactly one, one level up — [Bundle Change Log](../log.md). A directory here never has its own.