feat: add cursor-interactive element detection in snapshots (#374)

* fix: only warn about ignored flags when explicitly passed via CLI

The warning about launch-time options being ignored (when daemon is
already running) was incorrectly shown when options were set via
environment variables like AGENT_BROWSER_EXECUTABLE_PATH, even when
no CLI flag was passed.

Now the warning only appears when flags are explicitly passed on the
command line, not when values come solely from environment variables.

Fixes #372

* feat: add cursor-interactive element detection in snapshots

Add -C/--cursor flag to snapshot command that detects clickable elements
that don't have proper ARIA roles but are interactive based on:
- cursor: pointer CSS style
- onclick attribute/handler
- tabindex attribute

This helps with modern web apps that use custom divs/spans as buttons.

Fixes #366

* fix: add cursor option to getSnapshot type signature

cli/src/output.rs

@@ -905,6 +905,7 @@ Designed for AI agents to understand page structure.
 
 Options:
   -i, --interactive    Only include interactive elements
+  -C, --cursor         Include cursor-interactive elements (cursor:pointer, onclick, tabindex)
   -c, --compact        Remove empty structural elements
   -d, --depth <n>      Limit tree depth
   -s, --selector <sel> Scope snapshot to CSS selector
@@ -916,6 +917,7 @@ Global Options:
 Examples:
   agent-browser snapshot
   agent-browser snapshot -i
+  agent-browser snapshot -i -C         # Interactive + cursor-interactive elements
   agent-browser snapshot --compact --depth 5
   agent-browser snapshot -s "#main-content"
 "##