* develop:
  Fix streamlit#1230: OSError not caught when writing cache to disk (streamlit#8)
  Improve caching code (streamlit#2)
  Remove incorrect background of code inside error messages (streamlit#4)
  Fix line number in error message (streamlit#3)
  Update README.md
  Implement Caching object to support running code blocks only once (streamlit#1)
  Update README.md
  Add font licenses to NOTICE (streamlit#1267)
  Clean up repo for open source release. Remove unecessary folders. (streamlit#1266)
  Fix st.cache (streamlit#1273)
  Close streamlit#1092 (streamlit#1270)
  Change license header in variables.scss so it's compatible with scss-to-json. (streamlit#1268)
  Sidebar (streamlit#1224)
  Add Apache license and update all license headers (streamlit#1265)
  Handling objects with empty docs in st.help (streamlit#1261)
  Enhance Mochawesome report with screenshots (streamlit#1263)
  Add LICENSES file (streamlit#1262)

* Streamlit pink -> red70, normal text -> gray85

* Update font sizes

* Change fonts to Source Sans/Serif/Code Pro

* Add font files to Streamlit

* Update test snapshots

* Streamlit pink -> red70, normal text -> gray85

* Update font sizes

* Refactor labels and remove when nullsy (to fix settings dialog)

* Add snapshot tests (but no spapshots yet)

* Move WidgetLabel to its own file

…ions

Addresses three suggestions from PR #12807 review:

1. Simplify test cases (suggestion #2)
   - Reduced from 9 parameterized tests to 3 focused tests
   - Removed fragment and expander contexts (regression only in containers)
   - Eliminated parameterization that made test app hard to read
   - Simple, clear structure with named containers

2. Add deterministic width assertions (suggestion #3)
   - stretch: Container width=600, expect ~580-600px (allows padding)
   - content: Figure 6.4in @ 100 DPI = 640px, expect ~620-640px
   - pixel: Explicit width=500, expect ~480-500px
   - More stable than arbitrary >200px threshold

3. Clean up unnecessary comments (suggestion #4)
   - Removed comments that just describe next line
   - Kept meaningful comments explaining test logic and expectations
   - Improved readability

Test structure:
- 3 regression tests in containers only
- Specific figure size (6.4in x 4.8in at 100 DPI)
- Known container width for stretch test
- Deterministic assertions with reasonable margins

Note: Suggestion #1 (use_container_width check) addressed with explanation
in PR comment - current logic is correct for the new widthConfig system.

…ions

Addresses three suggestions from PR #12807 review:

1. Simplify test cases (suggestion #2)
   - Reduced from 9 parameterized tests to 3 focused tests
   - Removed fragment and expander contexts (regression only in containers)
   - Eliminated parameterization that made test app hard to read
   - Simple, clear structure with named containers

2. Add deterministic width assertions (suggestion #3)
   - stretch: Container width=600, expect ~580-600px (allows padding)
   - content: Figure 6.4in @ 100 DPI = 640px, expect ~620-640px
   - pixel: Explicit width=500, expect ~480-500px
   - More stable than arbitrary >200px threshold

3. Clean up unnecessary comments (suggestion #4)
   - Removed comments that just describe next line
   - Kept meaningful comments explaining test logic and expectations
   - Improved readability

Test structure:
- 3 regression tests in containers only
- Specific figure size (6.4in x 4.8in at 100 DPI)
- Known container width for stretch test
- Deterministic assertions with reasonable margins

Note: Suggestion #1 (use_container_width check) addressed with explanation
in PR comment - current logic is correct for the new widthConfig system.

The input element is always mounted in the DOM (never conditionally
rendered), just toggled between enabled/disabled states. Therefore,
requestAnimationFrame is not needed for focus management - we can
focus the element directly.

Resolves PR #12834 comment #4

Removed customizable strings from ChatComposer to match ChatAudioRecorder.
This pattern was over-engineering - no i18n system exists yet and it adds
unnecessary complexity. Now uses hard-coded aria-labels directly.

Also restored requestAnimationFrame in focusInput after tests proved it's
necessary. RAF ensures focus happens after click events fully process,
preventing race conditions when transitioning focus from buttons to input.

Resolves PR #12834 comment #7
Addresses PR #12834 comment #4