fix(cache): declare the provider env overrides that must invalidate the cache

[ozymandiashh]

Fixes #920.

computeEnvFingerprint() hashes only what PROVIDER_ENV_VARS declares, so the nine providers that honor an undeclared env var never invalidated their cache section: point KIRO_HOME at a second profile and CodeBurn keeps serving the first profile's sessions, reports nothing from the new root, and says nothing about it. Declared now — the nine reported overrides, the adjacent OS-set path vars that resolve a discovery root on Windows and Linux (Claude, IBM Bob, Open Design, Kilo Code), and Cursor's parse budget. Fourteen file-backed providers re-parse once as a result, which the changelog calls out.

Two things the issue did not anticipate, both found by review and verified on the code before acting:

Copilot is deliberately left undeclared. Declaring any of its nine reads moves its fingerprint, and getOrCreateProviderSection keeps only cached entries whose source path is gone — but OTel discovery returns one source per DB file (copilot.ts:1935) and that DB keeps existing, so the entry would be dropped and re-parsed, destroying conversations Copilot has since pruned from the DB that only the cache still holds. That trades a staleness bug for a data-loss bug. Its reads are allowlisted with that reason, the map documents it, and a test pins the invariant so nobody "completes" the map before the durable carry-forward learns to merge instead of drop. Follow-up below.

The Vercel gateway credential is declared, despite being a network provider. servedSources is seeded with every discovered source (parser.ts:2875) before the network branch, and the re-fetch (parser.ts:2888) only runs when !readOnly — so a read-only refresh serves the cached report straight from the section, and an undeclared credential keeps reporting the previous account's usage after a swap. Doctor redacts credential values to <set> at collect time, so a key cannot reach terminal output or the JSON report.

codeburn doctor needed a matching model, since it treats every declared-and-set var as a deliberate override. It now distinguishes three kinds: ambient Windows paths (APPDATA, LOCALAPPDATA) are hidden — Windows sets them for every process, so naming them would tell every Windows user their discovery runs under an override; parse-only settings (CODEBURN_CURSOR_MAX_BUBBLES, KIMI_MODEL_NAME) stay in Details but never get blamed in a NOTHING FOUND verdict, since neither relocates anything; the XDG vars stay fully visible, because they are opt-in and a set value is a real user override — suppressing them made doctor answer a deliberately relocated XDG_DATA_HOME with "tool likely not installed".

The issue asked for a test that stops this recurring, and tests/provider-env-declarations.test.ts is it: every process.env read in src/providers must be declared for the provider(s) that file serves, or allowlisted with a reason. It resolves bracket literals, dot access and process.env[CONST] indirection (open-design's ENV_DIR), fails loudly on any read it cannot resolve rather than skipping it, and fails when a read-bearing provider file is missing from the file-to-provider map. Allowlist entries are keyed file:VAR, so silencing a var in one file cannot mask another file's undeclared read.

Verification. tsc --noEmit clean; 117 tests green across the three affected files. Every new test was checked by breaking what it protects and confirming it goes red — the guard against five planted defects (dot access, dynamic key, bracket literal, a removed declaration, an unmapped provider file), and each doctor/cache invariant against removal of the exact entry it pins. The nine reported (provider, var) pairs each move the fingerprint, with codex/CODEX_HOME as the control the issue used. Note for CI: this repo's full suite is flaky under parallel load independent of this change — on a clean checkout at the base commit it fails a varying set (cache-refresh-lock, cli-json-daily, spend-flow), all passing in isolation.

Follow-ups, deliberately not in this PR:

• The durable carry-forward should merge cached durable turns with a re-parse instead of dropping present sources, after which Copilot's nine vars can be declared and their allowlist entries removed. Today any Copilot fingerprint change — including a PROVIDER_PARSE_VERSIONS bump — can lose pruned OTel history.
• quickdesk sets durableSources: true but is absent from DURABLE_PROVIDER_NAMES. Untouched by this PR (neither its declarations nor its parse version change here), but it is the same latent hazard.
• cursor-agent declares XDG_DATA_HOME without reading it. Kept deliberately — removing it would force a re-parse to fix nothing — but worth cleaning up whenever that provider next migrates.