Add reusable Python guide bases and family snippets - #1915

All four review threads are addressed and resolved. New commits: 4f48fb4 for the guide-base fixes, d477857 on prerequisite #1914 for shared review/CI fixes, and normal merge 19ae6ef here. No force push.

Validation on the merged source: 152 buildSrc tests, 13 Python script tests, generation of all 16 declared Python guide projects/test scripts, and fresh-output Build tasks for all four documentation-only cloud database guides pass. The Java MCP HTTP suite also passes both existing tests, including the corrected tool-description assertion. No local native image build.

The latest hosted Python script and Python generation checks pass; the general 32-guide matrix is still running. The previous AWS failure was caused by missing output parent directories, now reproduced and fixed in the shared generator rather than bypassed in CI.

Latest-head hosted CI is now green on 19ae6ef: all 32 guide matrix jobs pass, as do matrix generation, Python script tests and Python guide generation. All four review threads are resolved. Shared fixes remain in prerequisite #1914 and are normally merged here.

One Oracle many-to-many JVM job failed during the first cold container startup, then passed on the unchanged-source failed-job rerun. Its original quiet Gradle log did not retain the test exception; the timing matches the existing 60-second Test Resources client deadline, but that remains an inference rather than a confirmed timeout diagnosis or a newly fixed module bug. No timeout, assertion, retry policy or test-skip workaround was committed.

Local checks also pass: 152 infrastructure tests, 13 Python script tests, both existing Java MCP HTTP tests, all 16 declared Python guide generations and the four fresh-output docs-only cloud database builds. New commits only; no force push or local native image build.

Addressed the three new findings in review 5434341593 through new commits, without rewriting history:

• The shared selector correction is in prerequisite Add shared infrastructure for independently reviewed Python guides #1914, commit 1ffbfa7, imported by normal merge cd13c40. The real DefaultGuideParser regression shows that omitted child languages default to Java/Groovy/Kotlin, so they do not inherit Python from a base. The actual gap was inherited applications with explicitly enabled Python, plus omitted apps being incorrectly treated as an implicit application. The selector now matches the sorted application merge. New controls reproduce three failures before the fix and pass afterward.
• Both master-only Python workflow path lists include gradle/local-composite-builds.gradle.
• Commit ecbc39a changes the OpenAPI TOML block to only-for-languages:python. The JVM properties block is unchanged. Its source-contract regression fails with the old marker and passes with the fix; generator filtering is also checked for Java/Groovy/Kotlin/Python. No unsupported language variants were enabled.

Local checks on the merged head: 153 infrastructure tests and 19 Python script checks pass; both current Java OpenAPI guides render successfully (three Gradle/Maven pages checked: properties configuration present, no TOML or unresolved resource includes). No native image was built. Fresh hosted checks are running on cd13c40; the previous head’s green CI is not being reused as evidence for this head. #1914 must still merge first.

Addressed all four findings in the newest review 5434888907, including both summary-only items. New shared commit 12cbce0 on prerequisite #1914 fixes effective-metadata script inputs and both mixed-case underscore guards; commit 7ea7ae0 fixes distribution cleanup across supported languages and the Weather wording. Normal merge 33051ba imports the shared changes. No force push.

Reproducers were added before production fixes and recorded in issues #1923, #1924 and #1925. All 156 infrastructure tests pass with zero failures/errors/skips; 29 stdlib script tests pass, including 36 timing subcases. All 16 existing master Python project/script tasks regenerate, and a second unchanged run is up-to-date. The existing distribution and MCP Weather Stdio Build tasks also pass locally with native execution explicitly excluded. Timing tests use fake commands, not containers/images.

Both new inline threads have been replied to and resolved. The previous-head hosted MCP Weather Stdio failure was Maven Central HTTP 403 for the MCP dependency and Maven distribution, before application tests ran; it was not a reproduced source failure. Fresh CI is running on 33051ba, so I am not claiming its guide matrix is green yet.

This PR remains a draft. Its master diff includes unmerged #1914 infrastructure plus multiple reusable guide families; that is why it is much larger than a per-guide PR. Individual guides remain separate contributions and should list only the shared prerequisites they actually need. No split, closure or merge was performed.