feat: add anchored menu resizing and adaptive toolbar

[exterminatorrat]

Add native menu-panel resizing and keep formatting commands reachable as the panel changes width.

• Resize from panel edges and corners while retaining the top/status-button anchor, using the screen’s usable bounds instead of an 800-point ceiling.
• Keep Delete in a fixed trailing slot while earlier commands move into measured, ordered overflow. Preserve picker state, actions, shortcuts, accessibility, and the published hover style.
• Defer forced display only during live dragging and reuse diagonal cursors, while retaining synchronous frame adoption, cancellation, and release handling.
• Preserve larger saved dimensions during smaller-screen presentation and no-op resize gestures; persist a genuinely changed size once.
• Advance VERSION to 1.0.16-beta.1 with the matching changelog entry.

This is a focused 13-file port onto public main at d5f35ae24bc4bb78612aa348542b3c6a694776a7. It preserves the merged toolbar hover and editor blur, inline images, compact file UI, pinned-title/checklist layout, tab selection, and the accumulated editor features rather than publishing the older development history.

Verification

• The final corrected source passed all 2,445 tests across 34 suites locally, including the previously deferred integrated native coverage. The focused seven-test batch also passed.
• Initial CI exposed two test-harness issues: four resize fixtures assumed more screen space than the runner provides, and toolbar/picker helpers searched unrelated fixture windows. The correction changes only those test fixtures and owner-scoped lookups; product code and existing behavior assertions are unchanged.
• The new simultaneous wide-decoy/narrow-target regression passed with the fix and failed under a controlled restoration of the old global lookup. All protected process identities were preserved and every owned test host exited after each run.
• Fresh independent GPT-6 Astra/xhigh review approved the product diff, then separately approved the exact test-only correction and inspected its passing native evidence with no findings.
• Debug and Release builds, all 26 build-identity tests, and the identity-policy check passed for the integrated product source; subsequent changes are test-only. The current test graph builds, dependency lock remains unchanged, and whitespace checks pass.
• On f7fdd32, Enhanced Local CI passed and the standard job passed all 2,445 tests plus release-build and packaging steps. The standard job then exhausted its 30-minute budget while the final validator reran the full suite. Its budget is now 60 minutes; every check and the Enhanced job are unchanged. Fresh independent Astra review approved this one-line workflow correction.
• Both hosted jobs passed on 173f29aa6f852518a119dd990c3375f97de4d264; no test or packaging gate was skipped.

Visual evidence

The narrow image is a native production-view fixture from the public port; it predates only the persistence correction and inherited hover integration. The wide image is from the user-tested Build 69 donor with synthetic notes. Neither is a newly packaged final-head app. No FPS improvement, physical 2× display coverage, or exhaustive accessibility-variant coverage is claimed.

Wide panel in the user-tested Build 69 donor

The existing mixed font-size placeholder clipping limitation is unchanged. No new local package, release, accepted-build change, development-pointer advancement, or PR merge is included.