fix(sessions): highlight every skill chip in submitted prompts

[adboio]

Problem

Reported in Slack: once a prompt is submitted, only the first skill in the prompt keeps its chip highlight — later skills render as plain text. In the input box, all of them are highlighted. This is a purely cosmetic inconsistency in how a submitted user message is rendered in the thread.

Changes

Submitted prompts flatten their <skill … /> tags to plain /name text before the thread renders them, but the rendered-message chip parser (parseFileMentions.tsx) only matched a slash command anchored to the very start of the string (a non-global regex used with a single .match()). Any second-or-later /skill fell through to plain markdown.

The parser now scans for every slash command with a global, non-anchored regex and merges those matches with the existing mention-tag matches (files, folders, GitHub refs, error context), sorted by position, so each chip renders regardless of order.

How did you test this?

Added parseFileMentions.test.tsx covering multiple slash commands, non-leading commands, mid-word slashes (not matched), and slash commands interleaved with file mentions. Ran:

• vitest run parseFileMentions — 6 passed
• vitest run UserMessage — 5 passed (existing suite still green)
• biome lint on the changed files — clean

Automatic notifications

• Publish to changelog?
• Alert Sales and Marketing teams?

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Created with PostHog from a Slack thread

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[github-actions]

React Doctor found no issues in the changed files. 🎉

_{Reviewed by React Doctor for commit 29ac074.}

[charlesvien]

Closing stale PRs ahead of Friday's monorepo migration. If this is a mistake, rebase and reopen for review.