fix: improve dock close controls

[gvanderclay]

Summary

This started from a couple of rough edges in the dock UI.

Before this change, logcat could be closed with q, but <Esc> did nothing. Build output had no quick close mapping, so closing it meant leaving the buffer or using a window command. The dock controls window already used winfixheight, but the dock body did not, so the output area could still participate in height redistribution when other horizontal splits were opened or equalized.

After this change, logcat accepts both q and <Esc>, and build output gets the same close keys. Dock body windows also get winfixheight after they are created, matching the existing controls window behavior and the way Neovim treats quickfix-style bottom panels.

Changes

• Added buffer-local <Esc> handling for the logcat controls.
• Added buffer-local q and <Esc> close mappings for build output.
• Set winfixheight on dock body windows after those windows are created.
• Updated the keymap docs, the logcat/build guides, the changelog, and the related tests.

One behavior is intentionally unchanged: build output still closes through panel.close(). That matches the existing panel/window close path, so this PR hides the build dock but does not cancel or signal the running Gradle job.

The new mappings are buffer-local to the plugin dock buffers. If someone has their own <Esc> mapping for android-log or android-log-controls, they may need to apply it after the plugin sets its maps.

Testing

• ./scripts/run-tests.sh
• Relevant single test(s): panel, build stream, and logcat control coverage are included in the full test run

Docs

• README updated (if needed): no README changes
• docs/ updated (if needed)
• docs navigation updated for moved or renamed pages: no navigation changes
• command/config behavior reflected in reference docs
• user workflow changes reflected in guides
• CHANGELOG updated (user-visible changes)
• Config changes or new defaults noted: no config or default changes

Checklist

• Behavior is backward compatible or clearly documented
• No unrelated changes included