fix: read project attribution from the conversation's gizmo_id

A conversation in a project absent from CHATGPT_PROJECT_IDS exported into
no-project/ even though its own payload names the project. Found while
investigating the media 403s: bpi-f3-case-options sits in
g-p-6a4edf5160848191927b05da20f49151, which is not among the 13 configured
ids, so it filed under no-project.2026.

Both existing sources are bounded by what the user configured. The detail
response is not: it carries gizmo_id. Use it as a third fallback, after the
listing annotation and the project map, and cache the result into the map.
Attribution now stays correct with no list to maintain, and moving a chat
into a new project stops silently misfiling it.

Only g-p- ids are treated as projects — a custom GPT is not a project and
must not become a folder.

CHATGPT_PROJECT_IDS still matters for the listing pass: conversations that
live only inside a project never appear in the default listing, so an
unconfigured project's chats can be missed entirely. Each one is now
reported once per run with the id to add, which turns "some chats are
missing" into a line to paste.

8 tests cover precedence, the g-p- guard, map caching and the once-per-run
report. 318 pass.

CHANGELOG.md

@@ -11,6 +11,9 @@ Format follows [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - **`redact_secrets` missed compound key names.** It matched keys exactly, so `access_token`, `api_key`, and `session-token` passed through un-redacted into debug-logged response bodies; matching now applies per word ("keywords", "monkey", "tokenizer" stay intact).
 - **`tests/test_config.py::TestSessionLimiterConfig::test_defaults` depended on the developer's `.env`.** `load_config()` calls `load_dotenv(override=False)`, which re-populated the variable the test had just deleted — so it passed only on a machine with no `.env`. The test now stubs dotenv discovery.
 
+### Added
+- **Project attribution now reads the conversation's own `gizmo_id`.** Previously the project name came only from `CHATGPT_PROJECT_IDS`, so a conversation in a project you had not listed exported into `no-project/` even though its payload names its project. The detail response carries `gizmo_id`, so it is used as a fallback after the listing annotation and the project map — attribution stays correct without maintaining a list, and moving a chat into a new project no longer silently misfiles it. Only `g-p-` ids count: a custom GPT is not a project and must not become a folder. Each unconfigured project is reported once per run, naming the id to add, because the *listing* pass still needs `CHATGPT_PROJECT_IDS` — conversations that live only inside a project never appear in the default listing.
+
 ### Changed
 - Media download failures are bucketed as `forbidden` (403 — the file record survives) separately from `download-error`, so the run summary distinguishes it from `expired-or-missing` (404).