1.73.6

• defa8c4: fix(claude): repair corrupted thinking-block transcripts so resume preserves context (#1834)

Follow-up to the Issue #1834 recovery ("can we do even better?"). The previous
recovery (PR #1835) was reactive: a plain resume of a transcript poisoned by a
corrupted extended-thinking block ({ "type": "thinking", "thinking": "" } with a
kept signature) just repeats the 400 ... thinking blocks ... cannot be modified
error, so recovery almost always fell through to a fresh restart that discards
dozens of turns of accumulated context (50 turns / $3.84 in the second
reproduction log).

Recovery Phase 1 now proactively repairs the on-disk session transcript before
resuming: repairCorruptedThinkingBlocks (new
src/claude.session-transcript-repair.lib.mjs) strips the empty-text
thinking/redacted_thinking blocks from the session JSONL — a workaround proven
upstream (the Anthropic API permits omitting earlier thinking, just not
modifying it). When repair succeeds the resume keeps all accumulated context;
when it can't help, recovery still falls back to a fresh restart, so there is no
regression.

The repair is conservative: it never throws, only removes empty-text blocks (valid
signed thinking is untouched), never empties an assistant message, and writes a
one-time <session>.jsonl.pre-repair-backup before rewriting. The case study under
docs/case-studies/issue-1834 is updated with a second reproduction log and the
new repair-then-resume design.

Related Pull Request: #1836

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