Very large hostile transcripts render slowly in Reading view #437

A hostile published transcript can produce a note whose Reading view stays blank for several seconds.

Found by the PR #420 verification (V-420c, Obsidian 1.14.4, Linux, 2560x1440): 1,024 dense escaped paragraphs, each under the 2,000-character paragraph cap, render a 2.04 MB note. Its Reading view stays blank for 5.4-8.6 s in five of five opens. An equal-sized plain-text note opens in 0.14-0.16 s. The main thread stays responsive (this is a display delay, not a freeze), and Live Preview and Source open in at most 2.3 s and 0.3 s.

Real transcripts are far smaller: a 3-hour transcript of 43,200 words renders without delay, and the longest real paragraph across 154 published transcripts is 1,874 characters.

Possible fix: a total budget on the rendered transcript body before the note is written, for example 512 KiB (a 511 KB dense control opened in 1.35-1.49 s). It needs real-size data first: measure the rendered size of the longest real transcripts (5+ hour episodes) so a budget never truncates a legitimate transcript. Add a Reading-view regression that checks visible text, not just the view shell.

Severity: low. It needs an adversarial feed, and Obsidian stays usable.