feat: Claude Code CLI v2.1.105–v2.1.131 support (#274)

## Overview

Full audit and implementation of Claude Code CLI changelog entries from v2.1.105 through v2.1.131.

## Changes

### Implemented

- **#268** — Add `claude-opus-4-7` to the model picker, update all model pricing and context window sizes (also fixes a bug where `claude-opus-4-6` was coded as 200K context instead of 1M)
- **#269** — Expose effort level setting in UI via `--effort <level>` flag (`low`, `medium`, `high`, `xhigh`, `max`)
- **#273** — Expose prompt caching TTL env vars in UI (`ENABLE_PROMPT_CACHING_1H` / `FORCE_PROMPT_CACHING_5M`)
- **#267** — Add `PreCompact` hook support — emits `claude:pre-compact` event with "Compacting context..." toast and thinking state
- **#270** — Parse `plugin_errors` from stream-json init event and surface them as error output lines
- **#266** — Bump supported CLI version constant to `2.1.131`

### Closed as Not Applicable

- **#271** (`autoScrollEnabled`) — TUI-only setting; we manage our own scroll behaviour
- **#272** (`tui` fullscreen mode) — TUI-only setting; we use stream-json and never activate the TUI

## Testing

All checks pass (`./check-all.sh`) including frontend lint, format, type check, Vitest coverage, Clippy, and Rust test coverage.

✨ This PR was created with help from Hikari~ 🌸

Reviewed-on: #274
Co-authored-by: Hikari <hikari@nhcarrigan.com>
Co-committed-by: Hikari <hikari@nhcarrigan.com>

src-tauri/src/sessions.rs

@@ -81,7 +81,7 @@ pub async fn list_sessions(app: AppHandle) -> Result<Vec<SessionListItem>, Strin
     let mut items: Vec<SessionListItem> = sessions.iter().map(SessionListItem::from).collect();
 
     // Sort by last activity, most recent first
-    items.sort_by(|a, b| b.last_activity_at.cmp(&a.last_activity_at));
+    items.sort_by_key(|b| std::cmp::Reverse(b.last_activity_at));
 
     Ok(items)
 }
@@ -132,7 +132,7 @@ pub async fn search_sessions(app: AppHandle, query: String) -> Result<Vec<Sessio
         .collect();
 
     // Sort by last activity, most recent first
-    matching.sort_by(|a, b| b.last_activity_at.cmp(&a.last_activity_at));
+    matching.sort_by_key(|b| std::cmp::Reverse(b.last_activity_at));
 
     Ok(matching)
 }
@@ -348,7 +348,7 @@ mod tests {
         ];
 
         // Sort by last activity, most recent first (mimics list_sessions behavior)
-        sessions.sort_by(|a, b| b.last_activity_at.cmp(&a.last_activity_at));
+        sessions.sort_by_key(|b| std::cmp::Reverse(b.last_activity_at));
 
         assert_eq!(sessions[0].id, "new");
         assert_eq!(sessions[1].id, "old");