fix(app): stop remark-directive from eating colons in assistant messages

[bhuvansingla]

Problem

remark-directive (enabled for plugin directives like ::inline-vis{...}) also parses inline :name and block :::name directives. So any colon before a letter or digit — 9:30, key:value, :D — became a directive node.

remarkMessageDirectives only handled leaf (::name) directives. Text and container directives fell through to mdast-util-to-hast, which renders an unknown directive as an empty <div>. Inside a paragraph, that block element split the line and dropped the directive's text:

source:   at 9:30 today

before:   at 9
          ⏎  today      ← :30 gone, paragraph broken

after:    at 9:30 today

Fix

Handle all three directive kinds. Leaf directives mount as before; text and container directives are rewritten back to their literal source (text inline, container as a paragraph).

Display-only change — the persisted message text was already correct.

Tests

• Sentence with 9:30, a:b, :D renders verbatim in a single <p>, no injected block element (fails before the fix, passes after).
• :::note container renders as literal source text.
• reconstructDirectiveSource uses the right marker per kind (: / :::).