feat(confluence): make SVG processing optional to fix pycairo install… (#20115)

* feat(confluence): make SVG processing optional to fix pycairo installation issues

This change addresses installation failures on Debian/Ubuntu systems where
svglib 1.6.0 introduced breaking changes that require pycairo compilation,
which fails without gcc and cairo-dev system libraries.

Changes:
- Move svglib dependency to optional extras: pip install 'llama-index-readers-confluence[svg]'
- Add graceful degradation in process_svg() when dependencies unavailable
- Add FileType.SVG enum for custom parser support
- Add comprehensive migration guide with 4 different approaches
- Add unit tests for optional dependency behavior
- Add working examples for all SVG processing options
- Update README and CHANGELOG

Breaking Change:
SVG processing now requires explicit installation with [svg] extra.
Users who need SVG support should install with:
pip install 'llama-index-readers-confluence[svg]'

Backward Compatibility:
Maintained through graceful degradation - SVG attachments are skipped
with informative warnings when dependencies are not installed.

Fixes installation issues on systems without C compilers.
Tested: 3 tests passed, 1 skipped (expected when svglib not installed)

* Revert "feat(confluence): make SVG processing optional to fix pycairo installation issues"

This reverts commit ace7418.

* fix: pin svglib to >=1.5,<1.6

* bump: version to 0.5.0 for confluence reader

Author: manoj-bhamsagar

llama-index-integrations/readers/llama-index-readers-confluence/pyproject.toml

@@ -26,7 +26,7 @@ dev = [
 
 [project]
 name = "llama-index-readers-confluence"
-version = "0.4.4"
+version = "0.5.0"
 description = "llama-index readers confluence integration"
 authors = [{name = "Your Name", email = "[email protected]"}]
 requires-python = ">=3.9,<4.0"
@@ -41,7 +41,7 @@ dependencies = [
     "pillow>=10.2.0,<11",
     "docx2txt>=0.8,<0.9",
     "xlrd>=2.0.1,<3",
-    "svglib>=1.5.1,<2",
+    "svglib>=1.5,<1.6",
     "retrying>=1.3.4,<2",
     "llama-index-core>=0.13.0,<0.15",
 ]