fix(editor): stabilize image generation, layer editing and controls (#6992)

* fix(editor): stabilize image workflows and editing controls

* docs(editor): add desktop and mobile visual validation evidence

* fix(editor): synchronize quick edit model events and register imagePreferences in test coordinator

* fix(settings): enforce authoritative global image-gen policy and non-admin preference persistence

- Enforce authoritative administrator global image_gen_enabled disable in get_user_setting, do_generate_image, and image_editing_provider_available, preventing non-admin user preference overrides while preserving user-disabled opt-outs and can_generate_images privilege checks across direct, gallery, and editor paths.
- Filter non-admin preference persistence in saveImagePreferences to user preference keys only (image_model, image_edit_model, image_quality), preventing global policy toggles from leaking into user preferences.
- Return accurate 200 OK Response from saveImagePreferences after fallback persistence succeeds so settings UI displays 'Saved' instead of false 403 error, while retaining visibility of real errors.
- Load per-user preferences via readImagePreferences in initImageSettings so non-admin selections persist and display correctly after page reload.
- Clear per-user model preferences on successful admin save (POST /api/auth/settings) via PUT /api/prefs/{key} with value: null to prevent stale per-user preferences from shadowing updated global settings.
- Support clearing keys in PUT /api/prefs/{key} when value is null.
- Add comprehensive Python regression tests for global-disabled/user-enabled, global-enabled/user-disabled, and authorized generation, plus Node and browser regression tests for non-admin persistence, toggle isolation, reload, and admin clearing.

* fix(settings): invalidate shared appConfig cache near auth settings write

* fix(test): isolate test_tool_policy unit suite from external model endpoint state

* fix(test): isolate web_fetch failure regression from contextual follow-up heuristics

* fix(test): isolate test_tool_policy from cross-test approval gate state

Ensure _patch_loop_basics disables TOOL_APPROVAL_GATE_ENABLED so routing tests in test_tool_policy run in the intended opt-out posture even when prior tests populate DATA_DIR with skills or untrusted context. Remove unnecessary forced_tools and contextual web mock workarounds.

* fix(settings): isolate non-admin image toggle and surface preference cleanup errors

- Restrict image generation availability toggle to admin users in imageModels.js, disabling the switch for non-admins and reverting unauthorized changes with an explicit message.
- Separate non-admin image model preference saves from global toggle updates.
- Track preference cleanup results on admin save in imagePreferences.js, propagating cleanup failures instead of ignoring them.
- Require valid preference keys on 403 fallback so toggle-only attempts reject cleanly.
- Add /api/prefs route mock to test_image_model_settings_sync_both_directions_and_survive_reopening.
- Add regression coverage for admin cleanup failures and non-admin toggle rejection.

* fix(settings): reconcile admin toggle on partial cleanup failure and report errors

- In imagePreferences.js, distinguish pre-persistence failures from post-save cleanup failures using err.globalSaved and err.phase.

- In imagePreferences.js, notify listeners of global policy updates on partial success before propagating cleanup failure.

- In imageModels.js, retain the persisted target state on admin toggle when global persistence succeeds but cleanup fails.

- In imageModels.js, reconcile admin toggle with authoritative server state via readImagePreferences() after ambiguous or partial failures.

- In imageModels.js, report partial success accurately without suppressing preference cleanup error messages.

- Add regression coverage in test_settings_save_response_ok_js.py for cleanup HTTP 500, cleanup network rejection, successful cleanup, and failed global POST.

---------

Co-authored-by: pewdiepie-archdaemon <pewdiepie-archdaemon@users.noreply.github.com>
Co-authored-by: Alexandre Teixeira <general@alexandreteixeira.dev>

static/js/editor/stroke-tool-sliders.js

@@ -57,8 +57,11 @@ function wireToolSliders(prefix, fields) {
     // softness rises (the CSS already sets the radial gradient — we
     // just tween the inner solid radius to communicate the falloff).
     if (softPrev) {
-      const innerStop = Math.max(0, 60 - state[fields.softness] * 0.55);
-      softPrev.style.background = `radial-gradient(circle, var(--fg) 0%, var(--fg) ${innerStop}%, transparent 90%)`;
+      const amount = state[fields.softness];
+      const innerStop = Math.max(0, 60 - amount * 0.55);
+      softPrev.style.background = amount > 300
+        ? `radial-gradient(circle, var(--fg), color-mix(in srgb, var(--fg) ${Math.round(100 * 0.5 ** (amount / 300))}%, transparent) 50%, transparent 100%)`
+        : `radial-gradient(circle, var(--fg) 0%, var(--fg) ${innerStop}%, transparent 90%)`;
     }
   });
 }