docs: sync documentation with recent code changes

[YeatsLiao]

What does this PR do?

Syncs the documentation with code changes that have landed since the docs
were last updated:

• Configuration doc: add three missing entries — cluster-namespace,
  open-browser-when-ready and disabled-file-transfer-methods (including
  the enum values, the default [SCP] set by application.yml, and a note
  that the URL method only supports http/https after Restrict file transfer URL scheme to http(s) #392)
• What is Eclipse Jifa: update the server description from
  "SpringBoot 3" to "Spring Boot 4" (Bump Spring Boot to 4.1 #390)
• Changelog: flesh out the 0.3.0 section based on commits since 0.2.0
  (JFR analysis Feature: JFR Visualizer #252, GC log metrics feat: gc log analyzer supports metric #237, JDK 21 thread dump support support jstack file by JDK21 #370,
  jpackage Use "jpackage" to package "jifa" for local use (standalone mode) #336, Helm charts feat: jifa helm charts #272, dependency upgrades Bump Spring Boot to 3.3 #354/Bump to Eclipse MAT 1.16.1 #355/Bump Spring Boot to 4.1 #390, etc.),
  and add the previously missing 0.3.0 section to the Chinese changelog
• Fix a few typos in the Chinese configuration doc (ture → true, mixed
  English labels)

Both the English and Chinese docs are updated consistently. All descriptions
were verified against Configuration.java and application.yml.

Checklist

• Commits are signed off (DCO)
• Documentation-only change, no code affected