* refactor(engine): split convert_all's per-story plan into convert_plan
Resolves SonarCloud rust:S3776 on convert_all (cmd/variables.rs).
* refactor(pdf): split graphic_unclipped into per-kind helpers
Resolves SonarCloud rust:S3776 on graphic_unclipped (pdf/src/export.rs).
* refactor(compose): extract wrap exclusions and frame text area from frame_specs_placed
Resolves SonarCloud rust:S3776 on frame_specs_placed (compose/src/lib.rs).
* refactor(ui): extract command shortcut lookup from shortcut_key
Resolves SonarCloud rust:S3776 on shortcut_key (ui-egui/src/menus.rs).
Found while testing crates/engine/src/cmd/variables.rs:49
Co-Authored-By: Claude Haiku 5.5 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Parent-page text now uses the absolute page index as its cache key, so repeated page numbers and renumbering do not reuse another page's composition.
Validation: targeted canvas and PDF regressions, plus all six cargo xtask ci gates on main after #514 (1,179 native tests passed, 3 ignored; 15 crates passed WASM compilation checks).
Task: #523