fix(NATSRS-009-2): CU-86akbh48z Public Auth struct fields lack any doc comments or examples

[flamingo]

Closes findings from rule NATSRS-009-2 — Public Auth struct fields lack any doc comments or examples.

Draft — this is a starting point, not a finished change. The fix required judgment, so read it before trusting it.

#	Fix confidence	Finding	Location
1	🔴 55 low — review closely	Public Auth struct fields lack any doc comments or examples	async-nats/src/auth.rs:3

What changed — and what was deliberately left — is explained per finding as inline review comments on the lines each finding touched.

---

Run: https://product-hub.flamingo.so/admin/code-review
Run id: 06b1d724-91f9-455e-9eef-4cda91351dba

Merging this PR is recorded as acceptance of the rule that produced it;
closing it unmerged is recorded as rejection. Both feed rule health, so
closing a wrong suggestion is useful rather than merely tidy.

ClickUp task: CU-86akbh48z NATS async-nats and CI review findings (10 PRs)

[flamingo]

🦩 What this fix changed, finding by finding

1 finding(s) fixed in this draft — 1 explained inline on the diff; 1 low-confidence hunk(s) need close review before merging.

[flamingo]

🦩 🟠 Public Auth struct fields lack any doc comments or examples

Added /// doc comments to the Auth struct definition and each of its public fields (jwt, nkey, signature, username, password, token) as well as the crate-private signature_callback field in async-nats/src/auth.rs, describing their purpose and noting the mutual relationships (jwt+signature/signature_callback, username+password, token as alternative). This is a documentation-only change with no functional modifications. Confidence is not higher because the exact mutual-exclusivity semantics and exact server-side behavior are inferred from field names and typical NATS auth patterns rather than verified against server documentation, so a maintainer familiar with the precise auth flow should review the wording for accuracy.

🤖 Prompt for AI agents

In async-nats/src/auth.rs around line 3, review and complete this code-review fix: Public Auth struct fields lack any doc comments or examples.
What the draft fix changed: Added `///` doc comments to the `Auth` struct definition and each of its public fields (`jwt`, `nkey`, `signature`, `username`, `password`, `token`) as well as the crate-private `signature_callback` field in `async-nats/src/auth.rs`, describing their purpose and noting the mutual relationships (jwt+signature/signature_callback, username+password, token as alternative). This is a documentation-only change with no functional modifications. Confidence is not higher because the exact mutual-exclusivity semantics and exact server-side behavior are inferred from field names and typical NATS auth patterns rather than verified against server documentation, so a maintainer familiar with the precise auth flow should review the wording for accuracy.
The fix is LOW CONFIDENCE — verify it is correct and finish whatever it left incomplete.

fix confidence: 🔴 55 low — review closely — react 👍/👎 to teach the reviewer