fix(change_request_v2): enforce reason-document uniqueness with models.Constraint

[gonzalesedwin1123]

Fixes #394.

What

spp.cr.type.reason.document declared its (cr_type_id, reason) uniqueness rule with the legacy _sql_constraints attribute, which Odoo 19 ignores entirely — the registry logs "Model attribute '_sql_constraints' is no longer supported" on every load and the constraint is never created. Duplicate per-reason document rules could be saved silently since 19.0.3.0.0 (release 2026.07). Full analysis in #394.

Changes

• spp_change_request_v2 (19.0.3.1.0 → 19.0.3.1.1):
  • Re-declare the rule as models.Constraint (same derived PG constraint name, spp_cr_type_reason_document_reason_uniq; no rename hazard since the legacy constraint never existed in any DB).
  • migrations/19.0.3.1.1/pre-migrate.py: deduplicate existing rules before the constraint applies — keeps the lowest-id rule per (cr_type_id, reason) (matching which rule _get_effective_required_document_ids() used at runtime) and logs each removal. Required because Odoo downgrades a failed ADD CONSTRAINT during upgrade to a schema warning, which would leave the constraint silently missing exactly on the databases that have duplicates.
  • Tests (test_reason_document_constraint.py, following the spp_programs/tests/test_sql_constraints.py pattern): constraint exists in pg_constraint, duplicate insert raises IntegrityError, different reasons / different types still allowed, legacy attribute is gone. Written first, TDD: 3 of 5 failed on the unfixed code.
• scripts/lint/check_odoo19.py: new odoo19.sql_constraints error flagging any class-body _sql_constraints assignment with the models.Constraint replacement hint — nothing in CI caught this holdout (the repo is otherwise fully migrated, 76 models.Constraint usages).

Verification

• ./spp t spp_change_request_v2: 0 failed, 0 error(s) of 330 tests; the registry _sql_constraints warning no longer appears in the log.
• TDD failing-first run (pre-fix): 3 failed, 0 error(s) of 5 tests — proving the constraint was absent and duplicates were accepted.
• Migration SQL exercised against a scratch Postgres 15: 7 rows / 3 duplicates → duplicates removed keeping lowest ids, ADD CONSTRAINT then succeeds.
• Lint rule verified to fire on the pre-fix code (change_request_type.py:604 reported as error) and to pass on the fixed file; ./spp lint, ruff, ruff-format clean on changed files.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 70.18%. Comparing base (0f9241f) to head (565e6f2).

Additional details and impacted files

@@           Coverage Diff           @@
##             19.0     #395   +/-   ##
=======================================
  Coverage   70.17%   70.18%           
=======================================
  Files         205      205           
  Lines       17751    17756    +5     
=======================================
+ Hits        12457    12462    +5     
  Misses       5294     5294           

Flag	Coverage Δ
spp_api_v2_change_request	66.53% <ø> (ø)
spp_base_common	91.07% <ø> (ø)
spp_change_request_v2	77.83% <100.00%> (ø)
spp_cr_type_assign_program	92.07% <ø> (ø)
spp_dci_demo	94.28% <ø> (ø)
spp_farmer_registry_cr	61.24% <ø> (ø)
spp_farmer_registry_demo	61.06% <ø> (ø)
spp_mis_demo_v2	70.38% <ø> (ø)
spp_programs	65.27% <ø> (ø)
spp_registry	87.22% <ø> (+0.07%)	⬆️
spp_security	69.56% <ø> (ø)
spp_starter_sp_mis	86.66% <ø> (ø)
spp_studio_change_requests	84.85% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...pp_change_request_v2/models/change_request_type.py	69.00% <100.00%> (ø)

... and 1 file with indirect coverage changes

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[emjay0921]

LGTM — approve (author to merge).

Correct root-cause fix: _sql_constraints → models.Constraint, matching the pattern already used 74× across the repo. Verified points:

• Complete repo-wide — after this PR the only real _sql_constraints class attribute left is the one removed here; the new odoo19.sql_constraints lint rule enforces it going forward and pre-commit passing green confirms zero holdouts.
• Migration is careful — pre-migrate.py dedups before ADD CONSTRAINT, keeps the lowest-id rule per (cr_type_id, reason) (matching _get_effective_required_document_ids()'s runtime behaviour), guards the pre-19.0.3.0.0 'table doesn't exist yet' case, and logs each removal — sidestepping Odoo's silent downgrade of a failed constraint-add.
• Tests are solid — 5 TDD tests (constraint in pg_constraint, duplicate raw-INSERT raises IntegrityError via the savepoint+mute_logger pattern, different reasons/types allowed, legacy attribute gone).
• Full changelog/version discipline (HISTORY.md, README.rst, index.html, manifest 19.0.3.1.0 → .1.1); all 32 CI checks green incl. the module's 330-test suite.

Minor non-blocking note: the new lint rule's doc_link (docs/principles/odoo19-compatibility.md#sql-constraints) points at a doc that doesn't exist in the repo — but every existing rule in check_odoo19.py uses that same path, so it's a pre-existing convention, not introduced here.