Allow authored structures in mixed biomes and score overrides (#71)

docs/WRITING_GRAMMAR.md

@@ -8,7 +8,7 @@ The supported order follows the representable subset of the [Legacy grammar audi
 
 Missing terrain, controller, weather, lighting, celestial, or the controller's minimum biome count is an **incomplete** warning, not an error: the compiler retains seed-selected traits for missing branches. An omitted terrain page uses a seed-selected profile compatible with authored feature pages, so changing the Age name cannot accidentally select Flat, Void, or Cave terrain for Rocks or Lakes. If no profile can support the writing, binding still rejects it. Native consumes no authored biome pages; Single consumes one; Tiled/Grid and Tiny–Huge require two, with seeded filler when pages are missing. From 0.5.1.0, known misplaced or repeated pages no longer block creation: the book keeps its original order, while the server repairs category order, uses the last single-choice controller, and stores a writing-instability score in the Age plan. A conflicting/repeated choice adds 500; an out-of-order page or misplaced modifier adds 100. Native ignores surplus authored biome pages and Single uses the first, with the conflict recorded as instability. Audited Legacy symbol modifiers also add 500 for each Bright Lighting page and 100 for each Mineshafts, Nether Fortresses, Strongholds, or Villages occurrence after the third. Modern structures configured with the same rule are Bastions, Trial Chambers, Ancient Cities, Shipwrecks, Ocean Ruins, Pillager Outposts, Ruined Portals, Nether Fossils, Buried Treasure, and Trail Ruins. Every repeated structure page increases that structure's placement rate: probability-based structures multiply their chance, grid-based structures use a denser grid, and Strongholds add more positions to each ring and more positions overall. One page retains the vanilla placement rate. Authored structures can generate outside their vanilla biome set; each structure-page occurrence that requires this override adds 100 instability. Seed completion selects compatible biomes where possible. Other feature pages have no direct symbol cost. Incorrectly placed pages are **not** red-highlighted; their warning remains available as a tooltip. Unknown IDs, schema-v1 display-only symbols, unavailable dependencies/profiles, unsupported semantic effects or feature/material pairs, missing/extra Link Panels, and oversized writing still reject a new Age. The Binder disables output for those fatal errors and shows a red page indication where applicable. Rejected inputs remain removable.
 
-The plan stores the original writing order, the authoritative semantic value of each resolved symbol, the active repaired-page indexes, the writing-instability score, the Age seed, and a copy of the selected runtime profile. An explicit terrain page overrides random terrain selection; an omitted terrain uses a seed-selected compatible profile. The built-in Standard, Amplified, Cave, Island, Flat, and Void terrain pages select their matching generation resources. Age loading uses the frozen runtime profile and does not need the original symbol definition or runtime-profile JSON, though its referenced noise, biome-preset, and dimension-type registry entries must remain available. Existing bound books without plans are not reinterpreted. Page-free and Link-Panel-only books keep the pre-existing random path. Biome and environment pages affect new Ages, and the supported feature subset below is compiled into the same frozen plan. Runtime effects for a nonzero writing-instability score are not implemented yet.
+The plan stores the original writing order, the authoritative semantic value of each resolved symbol, the active repaired-page indexes, the writing-instability score, the Age seed, and a copy of the selected runtime profile. An explicit terrain page overrides random terrain selection; an omitted terrain uses a seed-selected compatible profile. The built-in Standard, Amplified, Cave, Island, Flat, and Void terrain pages select their matching generation resources. Age loading uses the frozen runtime profile and does not need the original symbol definition or runtime-profile JSON, though its referenced noise, biome-preset, and dimension-type registry entries must remain available. Existing bound books without plans are not reinterpreted. Page-free and Link-Panel-only books keep the pre-existing random path. Biome and environment pages affect new Ages, and the supported feature subset below is compiled into the same frozen plan. Nonzero instability can select a persisted provider plan; status effects, decay, lightning, explosions, meteors, burning, and test-enabled erosion run through the bounded Age-scoped scheduler described in [the runtime policy](INSTABILITY_RUNTIME.md).
 
 ## Supported feature pages (issue #35)