fix(review): clamp env-path trim below max; revert unwired scrollback raise (PR #138)

- UNBOUNDED-MEMORY: DEFAULT_TERMINAL_BUFFER_TRIM_BYTES from CODEMAN_TRIM_TERMINAL_TO
  had no relation to DEFAULT_TERMINAL_BUFFER_MAX_BYTES — setting only
  CODEMAN_MAX_TERMINAL_BUFFER=2097152 left the 24MB trim default in force, making
  BufferAccumulator.trim() (slice(-trimSize)) a no-op: unbounded growth past the cap
  plus a full string re-join on every append (O(n²)). Trim default is now clamped to
  75% of the resolved max (the 24MB/32MB default ratio, preserved as hysteresis);
  regression test re-evaluates the module under the env via vi.resetModules.
- OVERCLAIM: reverted DEFAULT_TERMINAL_SCROLLBACK_LINES 100k -> 50k — it has zero
  consumers; browser xterm scrollback is the separate hardcoded DEFAULT_SCROLLBACK
  (50k) in constants.js and deliberately stays 50k (mobile-memory hazard). The tmux
  history-limit raise (50k -> 100k) and PTY 32MB/24MB raise remain (those are wired).
  Module docstring now claims only what is wired; fixed the stale tmux-manager.ts
  comment saying the tmux limit "matches the xterm-side default in constants.js".

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/tmux-manager.ts

@@ -1202,7 +1202,8 @@ export class TmuxManager extends EventEmitter implements TerminalMultiplexer {
             /* Already set globally as fallback */
           }),
         // Raise tmux scrollback from its 2000-line default so re-attach preserves
-        // more context. Matches the xterm-side default in constants.js.
+        // more context. Intentionally exceeds the xterm-side DEFAULT_SCROLLBACK (50k
+        // in constants.js), which stays lower to protect browser/mobile memory.
         execAsync(`${this.tmux()} set-option -t "${muxName}" history-limit ${historyLimit}`, {
           timeout: EXEC_TIMEOUT_MS,
         })