feat: opt-in chat bubble layout (closes #336) (#403)

* feat(ui): opt-in chat bubble layout

Closes #336.

Adds a settings toggle that right-aligns user messages and left-aligns
assistant replies. Off by default - the current full-width layout is
friendlier to code blocks and tool output, so bubbles are strictly
opt-in per the maintainer note on the issue.

Wiring follows the existing token-usage / cli-sessions pattern:

- api/config.py: new bubble_layout bool in _SETTINGS_DEFAULTS and
  _SETTINGS_BOOL_KEYS, validated + persisted like the rest.
- static/style.css: .bubble-layout gated selectors using :has() to
  tag msg-rows by .msg-role.user / .msg-role.assistant without any JS
  changes to message creation. User rows get align-self: flex-end,
  max-width: 75%, and a row-reverse header; assistant rows flex-start.
  A 700px media query widens the max to 92% on narrow screens.
- static/index.html: new checkbox with i18n keys next to the existing
  token-usage toggle.
- static/panels.js: loads the setting into the checkbox, saves it
  back, and toggles body.bubble-layout immediately on save.
- static/boot.js: applies the class on initial load so refreshed
  tabs honor the persisted setting without a flash.
- static/i18n.js: English label + description.

Test suite errors are environmental (test server fails to start on
port 8788 on main as well).

* i18n(es): add Spanish translations for bubble_layout setting

* fix+test: boot.js bubble-layout reset on failure; add 22 tests for issue #336

* docs: v0.50.24 release — version badge and CHANGELOG

---------

Co-authored-by: Matt Van Horn <455140+mvanhorn@users.noreply.github.com>
Co-authored-by: Nathan Esquenazi <nesquena@gmail.com>

CHANGELOG.md

@@ -1,5 +1,16 @@
 # Hermes Web UI -- Changelog
 
+## [v0.50.24] feat: opt-in chat bubble layout (closes #336)
+
+- `api/config.py`: Add `bubble_layout` bool to `_SETTINGS_DEFAULTS` (default `False`) and `_SETTINGS_BOOL_KEYS` — new setting is opt-in, server-persisted, and coerced to bool on save
+- `static/style.css`: 11 lines of CSS-only bubble layout — user rows `align-self:flex-end` / max-width 75%, assistant rows `flex-start`, all gated on `body.bubble-layout` class so the default full-width canvas is untouched; 700px responsive rule widens to 92%
+- `static/boot.js`: Apply `body.bubble-layout` class from settings on page load; explicitly remove the class in the catch path so the feature stays off on API failure
+- `static/panels.js`: Load checkbox state in `loadSettingsPanel`; write `body.bubble_layout` in `saveSettings` and immediately toggle `body.bubble-layout` class for live preview without a page reload
+- `static/index.html`: Checkbox in the Appearance settings group, positioned between Show token usage and Show agent sessions
+- `static/i18n.js`: English label + description keys; Spanish translations included in the same PR
+- `tests/test_issue336.py`: 22 new tests covering config registration, JS class management in boot and panels, CSS selectors, HTML structure, i18n coverage for en+es, and API round-trip (default false, persist true/false, bool coercion)
+- 1003 tests total (up from 981)
+
 ## [v0.50.23] Add OpenCode Zen and Go provider support (fixes #362)
 
 - `api/config.py`: Add `opencode-zen` and `opencode-go` to `_PROVIDER_DISPLAY` — providers now show human-readable names in the UI instead of raw IDs