fix: salvage partial L3 abstraction drafts

[RerankerGuo]

Description

Fixes #1668.

L3 abstraction now normalizes partially structured provider output before deciding whether to reject it. Salvageable drafts can use string or object entries for environment, inference, and constraints; common label, description, and evidence aliases are normalized; tag strings are split into arrays; and a missing title can be derived from recovered content.

Drafts that remain completely empty after normalization still fail with LLM_OUTPUT_MALFORMED, so unusable output is not persisted.

Related Issue (Required): Fixes #1668

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

How Has This Been Tested?

• cd apps/memos-local-plugin && npm test -- --run tests/unit/memory/l3/abstract.test.ts passed with 8 tests.
• cd apps/memos-local-plugin && npm run lint passed.
• make format could not run in this environment because poetry is not installed: make: poetry: Command not found.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation, if applicable
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules