release: bump 0.9.5 -> 0.9.6 (#331)

Documentation release for the R binding. The library API and every indicator are
unchanged from `0.9.5`; only the R package's help pages change.

### What's in 0.9.6
- **R package documentation** (landed in #330): the twelve undocumented data-layer
  exports now have full man pages, the stale `AwesomeOscillatorHistogram` codoc is
  fixed, and a broken `push()` example is corrected — clearing the two `R CMD check`
  warnings r-universe reported for `0.9.5`. CI now runs `R CMD check` so doc drift
  fails the PR instead of reaching r-universe.

Pure version-string bump on top — `bump_version.py` touched 19 files. `cargo fmt`
clean.

Tag/publish waits for explicit GO (irreversible publish to crates.io / PyPI / npm
/ NuGet / Maven / Go / r-universe).

examples/java/pom.xml

@@ -6,7 +6,7 @@
 
   <groupId>org.wickra.examples</groupId>
   <artifactId>wickra-examples</artifactId>
-  <version>0.9.5</version>
+  <version>0.9.6</version>
   <packaging>jar</packaging>
 
   <name>Wickra Java examples</name>
@@ -21,7 +21,7 @@
     <dependency>
       <groupId>org.wickra</groupId>
       <artifactId>wickra</artifactId>
-      <version>0.9.5</version>
+      <version>0.9.6</version>
     </dependency>
   </dependencies>