nisse-review: read long files in parts; a retry starts afresh

From its failed review of #156: read_file stopped at 20,000 characters
with no way on, so the reviewer hunted each file's end a definition at a
time and ran out of turns; its retry carried every read before it, and a
model call timed out. Both drafts were lost.

- read_file takes a start line and says where the next part starts.
- Each run's view starts at its brief (Transcript.since); the log keeps
  the rest.
- A run out of turns with points drafted posts them as a partial review.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01J5Utyfzw7gF7UhjRDEtjTk

docs/Development-Plan.md

@@ -613,7 +613,9 @@ waits until two exist to compare. Moved, unchanged in behaviour:
   is checked every round, not only at startup.
 - **Reading (R3):** the repository at the PR's head and base, from Gitea's
   archives, unpacked into a scratch folder and read in Python (`read_file`,
-  `list_files`, `search_code`), and its issues (`read_issue`,
+  `list_files`, `search_code`; a long file is read in parts, `start` giving
+  the line, since a file cut at 20,000 characters left its end out of reach),
+  and its issues (`read_issue`,
   `list_issues`): no git, no shell, bound to the item's repository.
 - **A review:** starts from the PR, its commits, diff, comments, the issues it
   closes and CI; `comment` drafts a point on any line of any file (checked to
@@ -626,7 +628,10 @@ waits until two exist to compare. Moved, unchanged in behaviour:
   whether the review (marked with its head) was posted, and nothing is posted
   twice; with Gitea down, the item waits.
 - **Failures:** a failed run is tried again; after `tuning.review.attempts`, it
-  says so on the PR and waits for the next push.
+  says so on the PR and waits for the next push. Each run starts afresh from its
+  brief (the log keeps the rest), and one out of turns with points drafted posts
+  them as a partial review: on #156 the reviewer ran out of turns, then its retry,
+  carrying every read before it, timed out, and both drafts were lost.
 - **Access:** startup refuses an account that can push to, or administer, any
   repository it reads. The token needs `read:user`, `write:issue` and
   `write:repository` scopes; the account's read access is the limit.