fix(version): detect writable Python carriers

[tom-sapletta-com]

Fixes ticket-021. Goal now ignores import-only version re-exports, discovers conventional version.py/_version.py/about.py literal carriers, and keeps version sources writable. The application PR intentionally remains at 2.1.291; release metadata is a separate integration slice. Validation: 26 focused tests, 512 passed/2 skipped full suite, governance 0 errors/0 warnings.

[ifuri-validator-agent]

Deterministic Validator approval for exact head 05ef1167cf43e43fbe1b512ea9808a7ed458adfe.

Ticket: ticket-021
Correlation ID: ticket-021-version-detection-05ef116-20260810
Model: openrouter/z-ai/glm-5.2
Reviewed diff chunks: 2
Advisory LLM verdict: APPROVE
Advisory summary: Reviewed all 2 diff chunk(s). Ticket-021 correctly restricts Python version-file detection to writable literal __version__ assignments, ignoring import-only re-exports, and adds support for conventional version modules (version.py, _version.py, __about__.py). The regex is anchored to the start of a line and requires a literal string assignment, preventing false positives. Code changes are minimal, well-scoped, and consistent across both version_state.py and manager.py. Test results pass on Python 3.12 and 3.13. | Ticket-021 evidence and test additions for version source discovery. New tests cover import-only init.py deferral to conventional version.py modules and detection plus writability of conventional version modules. Test results show both Python 3.12 and 3.13 passing with no failures. No security issues observed in the visible chunk.
Advisory findings: none
The LLM output above is advisory and was not used as the approval trust root.
Merge was not requested or performed.

Decision record (recomputable)

DECISION D-021-2432
TICKET ticket-021
HEAD_SHA 05ef1167cf43e43fbe1b512ea9808a7ed458adfe
CORRELATION_ID ticket-021-version-detection-05ef116-20260810
ACTOR agent:ifuri-validator-agent[bot]
APPLIED_RULE P-CORE-015
INPUT author_login = "tom-sapletta-com"
INPUT observed_checks = ["test (3.12)=PASS","test (3.13)=PASS"]
INPUT required_checks = ["test (3.12)","test (3.13)"]
INPUT required_checks_source = "env/request"
INPUT reviewer_login = "ifuri-validator-agent[bot]"
VERDICT APPROVE AUTHORITY DETERMINISTIC
REJECTED REQUEST_CHANGES BECAUSE NO_UNSAFE_CHANGE_REASON_FOUND
ADVISORY llm_verdict = "APPROVE" MODEL "openrouter/z-ai/glm-5.2"
ASSERT VERDICT_AUTHORITY != "ADVISORY"