build(chat): consume partial-markdown 0.5.2 — streaming table headers (#739)

* docs(spec): streaming table-header rendering for partial-markdown

Projection-only optimistic header-row table in buildStreamingRoot — flips
paragraph→table at the first closed cell, eliminating the table blank/flash
during token-by-token streaming. Continues the 0.5.x open-line work; fix lands
in @cacheplane/partial-markdown, libs/chat consumes the release (no component
change — markdown-table.component already tolerates a header-only table).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* docs(plan): streaming table-header rendering implementation plan

8 tasks: cacheplane partial-markdown 0.5.2 (optimisticBlock projection,
eager first-closed-cell trigger, tablePending window, correctness guards,
chunk-fuzz, release) → libs/chat consumes 0.5.2 with a consumer anti-flicker
test. TDD, projection-only, no chat component change.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* build(chat): consume partial-markdown 0.5.2 — streaming table headers

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

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Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: blove