chore(release): prepare 0.6.10

[leehack]

Summary

• bump the package to 0.6.10 and add release notes for the Gemma 4, multimodal safety, and native sync changes since v0.6.9
• refresh release-facing docs and installation snippets so published docs match the upcoming package version
• update stale native bundle tag references from b8480 to b8638 where current docs describe the live hook configuration

Verification

• dart format --output=none --set-exit-if-changed .
• dart analyze
• dart test -p vm -j 1 --exclude-tags local-only
• ./tool/docs/build_site.sh
• ./tool/docs/validate_links.sh

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.92%. Comparing base (cfb2e0a) to head (30f04b8).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #105   +/-   ##
=======================================
  Coverage   76.92%   76.92%           
=======================================
  Files          68       68           
  Lines        8592     8592           
=======================================
  Hits         6609     6609           
  Misses       1983     1983           

Flag	Coverage Δ
unittests	76.92% <ø> (ø)

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