Bring README and TODO.md in line with next after the milestone merge (closes #132)

Docs only. TODO.md's Next Step no longer says open issues wait on
`next`: no implementation work is open, and the cache design waits on
sneak's review. The README is corrected where the code contradicts it:
where SRP lives and how the login subkey is derived, when email OTP is
used, how the auth token is encoded, the download retry's temporary
files, which CLI commands open a library, what `--exif` records, the ML
data fetch during `quak backup`, the default cache directory, and the
`408`/`429` retries.

Model: opus-5-5

TODO.md

@@ -14,13 +14,27 @@ pre-1.0
 
 # Next Step
 
-None: every issue still open is done on `next` and waits for it to reach `main`.
+None: no implementation work is open. The cache design,
+https://git.eeqj.de/sneak/quak/issues/36, waits on sneak's review.
 
 Tagging and releases are decided by sneak alone, and happen only when he
 declares one.
 
 # Completed Steps
 
+- 2026-09-29: Brought the README and this file in line with `next` after the
+  milestone merge (issue 132). The Next Step says no implementation work is open
+  and the cache design (issue 36) waits on sneak's review. README corrections:
+  `script/lint` and `script/test` have no host path, though `yarn test` does;
+  the SRP handshake uses `fast-srp-hap`, outside `crypto/`; the SRP password is
+  the first 16 bytes of a 32-byte subkey; email OTP replaces SRP when the
+  account has email MFA on; the auth token is sent as URL-safe base64 with
+  padding; each download attempt writes its own temporary file; `login`,
+  `whoami` and `logout` open no library; `--exif` records XMP and, for a JPEG,
+  EXIF, and no IPTC; `quak backup` still fetches ML data; the default cache
+  directory is the per-user one, not an XDG path on macOS; and `408` and `429`
+  are retried.
+
 - 2026-09-28: Tested the live-photo writer's fsyncs (issue 130). A test checks
   that the image's and the video's temp files are fsynced before either is
   renamed into place, and the directory after both renames, as the `writeAtomic`