fix: keep source release helpers outside GitHub

[imbajin]

Organization counterpart: hugegraph#67.

Purpose of the PR

Source releases currently carry GitHub automation files because SDK verification and Server fixture helpers live under .github. Excluding .github without moving those dependencies would break source packaging or its integration scripts.

Main Changes

• Exclude the entire .github/ directory and Hubble documentation screenshots from git archives.
• Move the existing SDK verifier and four existing Server fixture helpers into hugegraph-client/assembly/travis/. Update POMs, Dockerfiles, CI calls, imports, cache inputs and existing test fixtures. Keep verification behavior unchanged; no new script, framework or dependency.
• Keep Hubble frontend public/ and src/ resources. Keep README screenshot references relative; documentation images remain excluded from source archives.

Verifying these changes

• 90 existing Python tests completed (4 optional checks skipped), 15 runtime fixture tests and 32 installer tests passed. These use disposable fixtures/stubs, not real release artifacts.
• actionlint, shell syntax, POM XML parsing and git diff --check passed.
• Streamed git archive listing and independent review confirm .github and documentation screenshots are absent; all five required helpers and Hubble frontend resources are present. SDK verifier, release.py and service-wait.sh are byte-identical moves; fixture/manifest changes only adjust paths.
• No SVN artifacts were downloaded, extracted or executed locally; no local Java/Maven/Docker product build was run. PR CI is running.

Paired validator compatibility: apache/hugegraph-doc#524. Merge it before using the new Toolchain source candidates; it retains support for already-uploaded candidates.

Does this PR potentially affect the following parts?

• Other affects: source release archive contents and helper locations
• Nope
• Dependencies
• Modify configurations
• The public API

Documentation Status

• Doc - Done: README.md, hugegraph-hubble/README.md and docs/java17-migration.md paths updated.
• Doc - TODO
• Doc - No Need

Conceptual overview

Conceptual overview: relocate the SDK verifier and four build helpers before excluding .github and Hubble documentation images; retain frontend runtime assets. Merge validator compatibility in apache/hugegraph-doc#524 before using new candidates. Not test evidence.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 47.03%. Comparing base (41e8d71) to head (3cde1ee).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #813      +/-   ##
============================================
+ Coverage     44.85%   47.03%   +2.18%     
- Complexity     3332     4517    +1185     
============================================
  Files           377      602     +225     
  Lines         22498    29444    +6946     
  Branches       3006     3454     +448     
============================================
+ Hits          10092    13850    +3758     
- Misses        11338    14312    +2974     
- Partials       1068     1282     +214     

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[imbajin]

Current-delta source review: 8.5/10. The byte-identical verifier relocation and inspected Maven/Docker/CI consumers are consistent. P3: restoring relative screenshot links in README.md and hugegraph-hubble/README.md points retained documents back into export-ignored hugegraph-hubble/docs/images. The source archive loses these targets; the Hubble binary assembly also copies README* without that images directory. Please keep documentation references consistent with the delivered archive contents. This is documentation usability, not a confirmed build/runtime blocker; six references are not six independent defects. No artifacts or tests were executed.

[imbajin]

Confirmed the screenshot packaging comment. The relative image links remain in the repository READMEs, while the referenced images are omitted from the source archive and Hubble binary package. This documentation usability limitation is tracked separately and has not been fixed by the verifier relocation.