Own application state by reactive root and require complete CI

[qqrm]

AppContext now owns each App root's signals and ECS; charts retain that owner, disposal aborts its streams, and callbacks ignore disposed owners. TooltipData/LineVisibility are neutral UI data with compatibility accessors for gradual migration.

• Replace undefined zero-initialized GPU fixtures with safe geometry-only fixtures; exercise cache invalidation without GPU submission.
• Restore actual browser execution of existing tests and add lifecycle/remount tests. Repair exposed SMA indexing/period boundaries, precision at the zoom floor, and partial aggregate updates overwriting closed indicator values. Correct stale JSON/OHLC/positioning fixtures against current behavior.
• Require locked stable compilation, strict Clippy, Python, Rust browser/Node and deterministic WebGPU UI tests. The official WASM runner follows Cargo.lock and uses matching Chrome/ChromeDriver; every test binary runs even after a failure.
• Remove actor skips/automatic PR closing; pin verified Actions, restrict write permission to deployment and retain benchmark artifacts. Add dependency batches and exact-head native auto-merge policy; anchor test URL boundaries.

Validation on b5d343f: 118 Rust browser tests (including all 3 lifecycle tests), 1 Node test, 7 Playwright/WebGPU scenarios, 2 Python regressions and 6 policy tests passed. Locked check/strict Clippy, actionlint/zizmor and all four CodeQL analyses passed. Main scanner has marked all 18 previous alerts fixed (zero open). Post-merge workflow results are tracked separately.

Limits: 49 legacy plain/QuickCheck cases compile but do not execute in the WASM harness; one native-only performance case is excluded. Native runtime execution is not established. Renderer/render queue remain shared services; UI/ECS isolation does not establish independent GPU renderers or physical-device FPS. No local external browser, live provider call or release dispatch was used.

References: F:src/app_context.rs#L87-L175, F:src/ui_state.rs#L1-L54, F:tests/app_context.rs, F:DOCS/TESTS.md#L37-L43, F:.github/workflows/ci.yml.