fix(android): preserve editable-field metadata in snapshots

[AdzeB]

Summary

Android structured snapshots and get attrs now preserve native editable, password, hintShowing, and selection offsets, including explicit false/zero. Empty accessibility text remains value: ""; unavailable facts remain absent. Documentation explains availability and interpretation.

This extends #2066's internal hint handling. Selection offsets are not character counts or proof of value equality. Exact opaque-value verification remains separate (#2289); no new secret-value reads or fill-verification behavior are introduced.

Eight files changed: seven for field observations and one test-isolation repair in a separate commit. A pre-existing lifecycle test failure reproduced on the untouched baseline was fixed by mocking the consumed application-tools factory's prewarm facet, with causal red/green proof.

Closes #2288.

Validation

Final head: a6fa69a8c0cc3dcd83568db20f57fd13936c7eba.

• pnpm check:affected --run: all runnable checks passed, including format, lint, typecheck, layering, fallow, build, and 730 related test files / 5,609 tests. Native/device and coverage CI remain authoritative.
• Three field-metadata tests passed; reverting the implementation made two fail.
• Native build and live evidence at a4a9f5a1956cfa94812fd5216d90f444248210d5; no production code changed afterward. pnpm build:android passed. On an API-36 arm64 emulator with rebuilt 0.20.11-dev helper and isolated daemon, CLI snapshots preserved explicit booleans; a synthetic secure field's get attrs returned hintShowing: false and selection offsets 4/4 after fill. Its masked hint reported hintShowing: true before fill. Sessions closed.

[thymikee]

Two blocking production-route gaps remain at exact head a6fa69a8c0cc3dcd83568db20f57fd13936c7eba:

1. get attrs --level digest drops editable, password, hintShowing, selectionStart, and selectionEnd because SELECTOR_DIGEST_NODE_FIELDS in src/daemon/response-views.ts omits them. Digest is the supported token-cheap attrs response, so add these semantic fields and a digest-route regression covering explicit false/zero/empty plus omission when unavailable.

2. The helper emits selection offsets only inside if (node.isEditable()), but feat(android): expose editable-field metadata in structured snapshots #2288 requires every available nonnegative accessibility offset. Read-only selectable text can expose a valid selection independently of editability. Read and emit each nonnegative offset independently, and add a parser-to-snapshot regression for a non-editable selectable node; negative/unavailable values must remain absent.

The rest of the XML → parser → raw/regular snapshot route looks correct, and the live Android evidence is credible for the unchanged production commit. Final-head CI has not reported yet. Holding ready-for-human until these gaps are fixed.