fix: update vt100 0.15 → 0.16 to restore dim (SGR 2) attribute in snapshots (#16)

vt100 0.15 did not track the dim/faint attribute (SGR 2) at all — no
TEXT_MODE_DIM bit and no handler in sgr(). As a result, state_formatted()
never re-emitted ESC[2m, so text rendered as dim in the live session would
appear as normal-weight text after a detach/re-attach cycle.

vt100 0.16 adds TEXT_MODE_DIM and handles SGR 2 → set_dim(), and
state_formatted() correctly re-emits Intensity::Dim as ESC[2m.

Confirmed via byte-level comparison of live PTY output vs snapshot:
  ORIGINAL:  ESC[2mNo ESC[0m  (faint)
  0.15 snap: ESC[m  No        (dim lost)
  0.16 snap: ESC[m  ESC[2mNo  (dim preserved)

API changes in 0.16:
- screen.errors() removed → dropped from debug log format string
- parser.set_size(rows, cols) → parser.screen_mut().set_size(rows, cols)

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: ttak0422

Cargo.lock

@@ -16,7 +16,7 @@ log = "0.4"
 env_logger = "0.11"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
-vt100 = "0.15"
+vt100 = "0.16"
 
 [workspace]
 members = ["proto"]

Cargo.toml

@@ -64,7 +64,7 @@ impl Session {
     /// Resize the pty and VT parser.
     pub fn resize(&mut self, cols: u16, rows: u16) -> io::Result<()> {
         self.pty.resize(cols, rows)?;
-        self.parser.set_size(rows, cols);
+        self.parser.screen_mut().set_size(rows, cols);
         Ok(())
     }