feat: add vector store updates, content, and expiration

[franciscojavierarceo]

Summary

Synchronize this layer with its updated parent after main's AgentPipeline refactor (#274), preserving the immediate-base review boundary.

Stack layer 5 of 7: #34 foundation → #278 pgvector/CI → #280 contextual retrieval/reranking/configuration → #281 streaming Files → #282 store lifecycle/content → #283 durable batches → #284 streaming/SDK compatibility.

Base: codex/files-api (#281). Next: #283. Review against the immediate base and land from the bottom of the stack.

Add Vector Stores updates, file attribute updates, parsed original content, status-filtered pagination, and expiration to the in-tree file-search APIs. Nullable patches distinguish omitted fields from explicit null. Expired stores retain metadata and stop serving attachments/search while independent uploaded files remain available.

Serialize activity, policy updates, publication, and cleanup in SQLite/PostgreSQL. Recheck expiry after database lock waits and model calls to prevent late requests from reviving expired stores. Store original parsed content separately from overlapping/contextual chunks, and publish resolved attachment chunking in the OpenAI response shape.

Test Plan

Layer-specific implementation verification:

• All-feature focused core suites: 34 service, 17 model, 6 tool, and 5 lifecycle tests passed; 13 HTTP and 7 OpenAPI tests passed.
• Real PostgreSQL 17/pgvector 0.8.6: 13 integration and 4 schema tests passed, including contended-lock/model expiry and cleanup versus policy-extension races.
• Legacy parsed-content recovery regression covers a 900,000-word attachment originally ingested with 4096/0 chunking. A PostgreSQL round trip verifies omitted/value/null store updates.
• Core file-search units (32) and SQLite schema tests (6) passed.
• Strict OpenAI Python SDK 3.13.0 store updates/expiry and attachment attributes/content tests passed against the rebuilt server and local model fixtures.
• All-feature changed-crate/all-target clippy, formatting, and all pre-commit hooks passed.

After synchronization with #274: This updated layer passed locked all-feature workspace compilation, diff checks, and all-files pre-commit hooks. The combined stack in #284 passed 1,389 workspace tests, 31 PostgreSQL/pgvector tests, and 17 maintained SDK cases, plus the Rust 1.88 all-feature check and all-target workspace clippy. The pipeline integration review is complete. GitHub CI is rerunning for the updated heads; previous green checks apply to the prior revisions.