fix(chat): refine compact controls, settings, and update cues

[0xvincent]

Summary

• replace direct tab close controls with hover-only ellipsis menus, with deletion inside the menu
• place the borderless new-tab action directly beside the tab group
• move history and usage to the top-right and open Qoderian settings in a standalone plugin-owned window
• show a non-blocking badge beside the Qoderian mark when a newer stable GitHub release is available
• make composer status, model, external-context, and MCP panels fit narrow sidebars without clipping
• replace the clipped context arc with a complete circular meter and use a paperclip for external context
• unify header icon color and Lucide stroke treatment across history, usage, and settings
• apply a Codex-inspired visual pass to tabs, composer, messages, tool rows, floating panels, and the high-contrast circular send action
• follow the Obsidian language and use the maximum supported tab count for fresh installations
• remove the redundant restart-current-conversation icon while keeping its command-palette action

Verification

• npm run typecheck
• npm run lint
• npm run test:coverage -- --runInBand (164 suites, 3508 tests)
• npm run build
• npm run release:check
• Runtime UI verification in an active Obsidian vault: settings modal ownership, menu interaction, icon alignment/color, complete context ring, single-line narrow toolbar, adjacent new-tab action, full-width resize grip, and popover bounds
• npm run audit:prod — the unchanged dependency graph has existing advisories in fast-uri@3.1.5 and qs@6.15.2; this PR adds no dependencies

Safety

• No credentials, private vault content, internal URLs, or personal paths are included
• Network failure during the release check is silent and never blocks chat
• User-visible changes are documented in CHANGELOG.md

Interaction details

• A tab number remains the primary click target. Its ellipsis appears only on hover or keyboard focus, and selecting Close tab from the menu is the only pointer-driven delete action.
• The borderless plus action follows the scrollable tab group with a 4 px gap, so it stays visually connected without consuming a full tab slot.
• The update badge checks the latest stable Qoderian GitHub release once per plugin session. It stays hidden when the installed version is current and opens the matching release page when clicked.
• Composer height remains bounded between 140 px and 75% of the chat view. Double-click or Home restores automatic content-based sizing.
• Neutral surfaces, typography, icon weight, and the circular send action establish the Codex-inspired direction while preserving Obsidian theme variables.