fix(hooks): differentiate burst and edit-ratio heuristics on tool type

The burst counter incremented on any tool call <30s apart regardless of
tool type, so a bulk read of many files produced the same "Rapid-fire"
alert as a rapid-fire editing sequence. The edit-ratio check reported
"possible stuck/spiral" for any session under 10% edits past 30 minutes,
which a read-heavy analysis session satisfies structurally whether or not
the work is productive. Both mechanisms are confirmed in
docs/BRIEF-vurdering-v2.md, verification points 1a and 1b.

tool-tracker.mjs now tracks whether the current burst run consists only
of read tools and suppresses the rapid-fire alert for such runs. A
read-dominant session (>=70% reads) reports its low edit ratio as
context rather than as a stuck/spiral claim, and never as the sole
reason for a warning. Bursts involving Edit/Write/Bash and
non-read-dominant sessions behave exactly as before.

No new data is recorded: the differentiation uses tool_name, which
events.jsonl already logs. The privacy design is untouched.

Tests first (Iron Law): 5 cases in tests/tool-tracker.test.mjs, 3 of
which failed against the previous implementation, 2 of which are
regression guards that passed before and still pass.

Verified: node --test tests/*.test.mjs -> 263 pass, 5 fail. All 5
failures are the perf wall-clock assertions, which fail identically on
HEAD without this change (measured by stashing and re-running) — they
are a pre-existing property of this machine, not a regression.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011wMhJuPFUiWqKLSQjrzCXP

CHANGELOG.md

@@ -2,6 +2,24 @@
 
 All notable changes to this project will be documented in this file.
 
+## [Unreleased]
+
+### Fixed
+
+- **The burst and edit-ratio heuristics could not tell reading from editing**
+  (`docs/BRIEF-vurdering-v2.md` tiltak 1, verification points 1a/1b). A bulk
+  read of many files produced the same "Rapid-fire: N consecutive fast
+  interactions" alert as a rapid-fire editing sequence, and a read-heavy
+  analysis session was reported as "possible stuck/spiral" purely because its
+  edit ratio is structurally low. `tool-tracker.mjs` now tracks whether a
+  burst run consists only of read tools (`Read`/`Grep`/`Glob`/`NotebookRead`)
+  and suppresses the rapid-fire alert for such runs; a read-dominant session
+  (≥70% reads) reports its low edit ratio as context rather than as a
+  stuck/spiral claim, and never as the sole reason for a warning. Bursts
+  involving `Edit`/`Write`/`Bash` and non-read-dominant sessions are
+  unchanged. No new data is recorded — the differentiation uses `tool_name`,
+  which `events.jsonl` already logs.
+
 ## [1.2.2] — 2026-08-02
 
 ### Fixed