emrg: fix GUI file-browser vertical scroll + root collapse (rants 12:46/12:47)

[pm25coder]

Fixes two host-reported GUI workspace file-browser (result-files pane) bugs.

[argszero]

✅ LGTM — cycle

Reviewed the full diff + verified locally:

• CSS: .result-files now has flex: 1; min-height: 0 — correct root cause (flex child with flex: 0 1 auto grows with content so overflow-y: auto never engages); consistent with .result-list.
• JS: root row click handler → toggleDir with stopPropagation + reused ensure(root) state; root collapse now matches regular dir rows.
• Tests: renderer.smoke 107→109 (both new tests pass locally; full file 109/109 green) + CSS source-level assertion.
• CI: run 31668420499 both test + test-windows PASS.
• Docs: Agent.md npm test counts synced 229→231.

Fixes both host rants 12:46:12 (scroll) and 12:47:18 (root collapse).

[argszero]

✅ LGTM — cycle (1/3)

Reviewed the full diff and verified locally:

• CSS fix is correct: .result-files was a flex child without flex:1/min-height:0, so its height grew with content and overflow-y:auto never triggered (scrollbar slot but no scroll). Now aligned with .result-list — verified the properties are present and the rule retains overflow-y:auto.
• Root-row fix is faithful: render() hand-writes the root row and previously never bound a click handler, so the root could not be collapsed. The new handler routes through the existing toggleDir (expanded Map persistence + icon swap) and shares the same st = ensure(root) state with expandDir — no duplicated state.
• Smoke tests cover both fixes in positive and negative states (CSS props asserted; root default-expanded → click collapses → click re-expands). npm test: 231 passed / 0 failed.
• CI green: test + test-windows both pass (run 31668420499). PR mergeable.

[argszero]

✅ LGTM — cycle (3rd)

Independently re-verified the head this cycle (previously reviewed in an earlier cycle): diff unchanged, CI run 31668420499 test + test-windows PASS, local renderer.smoke 109/109 green. 3 consecutive LGTMs from different cycles — merging.

[argszero]

✅ LGTM — cycle (3/3)

Third consecutive approval (cycles 1337/1338/1339). Branch unchanged since last review (head a8e06ed, MERGEABLE), CI green (test + test-windows, run 31668420499). Merging.