fix(locales): polish Arabic translations (#175)

## Summary

- refine Arabic terminology for Genome, code intelligence, prompt
caching, cache-hit metrics, and model routing
- clarify UI wording for dock/undock, lean context, inline diffs,
telemetry, update verification, and terminal paste behavior
- keep the locale aligned with the latest 3,380-key English catalog at
100% coverage

## Scope

- `locales/ar.json` only
- 39 focused translation updates
- no source, workflow, or generated English catalog changes

## Upstream catalog note

The branch was created from `main` after commit `612d23e`, which had
already pruned several stale implementation tokens and fragmented TUI
keys identified during review. Remaining isolated generated fragments
such as `it` and `them` require changes in the private source catalog
and were intentionally not guessed in the Arabic locale.

## Validation

- `npx --yes bun@1.3.13 scripts/validate-locales.ts ar` — 100%
translated (3380/3380)
- `npx --yes bun@1.3.13 test scripts/validate-locales.test.ts` — 22
passed, 0 failed
- `git diff --check` — clean

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Co-authored-by: fares <aw674860@gmail.com>

Author: fares111111122