fix: expand Settings disclosure click targets

[exterminatorrat]

Stacked on #54 as the final layer of the coordinated stack. Make Privacy, Activity, Access, and Full build metadata easier to open without expanding the Settings scope.

• Use one shared plain Button style with a full-width rectangular hit area, horizontal/vertical padding, and a 36-point minimum header height.
• Toggle only the existing disclosure state; expanded content and its controls remain outside the header Button.
• Apply the style explicitly to the four requested disclosures. Leave Transfer, Settings search, focus routing, and existing focus outlines unchanged.
• Advance VERSION from 1.0.19-beta.1 to 1.0.20-beta.1 and retain every lower-layer changelog entry.

Verification

• The final combined source passed seven focused Swift tests, 26 identity tests, identity policy, the Debug build, strict formatting for the new files, and whitespace checks.
• Fresh independent GPT-6 Astra/xhigh review approved the exact seven-file diff against fix: make Agent Activity scrollbar trackless and edge-aligned #54. All five production/test files are byte-identical to the previously approved public port; integration reconciled only version/history metadata.
• The shared style is byte-identical to the recorded native fixture: 49 exact-once mouse transitions, two child/body cases plus one independent positive control, and nine AX assertions passed. This is mouse/AX evidence, not a complete native-suite pass; unrelated anchored keyboard diagnostics are outside this port.
• Existing tests are unchanged. No historical Settings redesign or donor history was imported.

Exact-style fixture evidence

Historical unfocused header render using the same shared style, not a newly packaged public app.

Full-suite GitHub CI remains a separate gate. No new package, app launch, release, accepted/development-pointer advancement, or merge is included.

[capy-ai]

The coordinated five-layer stack is green at the published, reviewed heads. Both hosted jobs—macOS build and tests and macOS Enhanced Local candidate gates—passed on every layer: 10 successes, no pending, failed, or skipped checks.

Layer	Verified head	Hosted run
#51	173f29aa6f852518a119dd990c3375f97de4d264	CI
#52	5e23ec214f8317e7a1bae72888343f215cc24bba	CI
#53	74a891933a4dd3a78a6fe75973d6845996ac1ad4	CI
#54	9f59f5faea94002838450281d4603669d3713983	CI
#55	a492aa0badaaf2631bddbbb282c168b403b464ff	CI

The native stack remains synchronized in order #51 → #52 → #53 → #54 → #55, with final product version 1.0.20-beta.1. Every PR remains open; no merge or merge queue was enabled. Local independent review approvals and the documented native-QA limitations remain as described in the individual PRs. This is source/CI readiness, not release or accepted-build promotion.