chore: remove unused imports, dead code, and stale comments

Mechanical cleanup — no behavior changes.

Unused imports removed:
- model_tools.py: import os
- run_agent.py: OPENROUTER_MODELS_URL, get_model_context_length
- cli.py: Table, VERSION, RELEASE_DATE, resolve_toolset, get_skill_commands
- terminal_tool.py: signal, uuid, tempfile, set_interrupt_event,
  DANGEROUS_PATTERNS, _load_permanent_allowlist, _detect_dangerous_command

Dead code removed:
- toolsets.py: print_toolset_tree() (zero callers)
- browser_tool.py: _get_session_name() (never called)

Stale comments removed:
- toolsets.py: duplicated/garbled comment line
- web_tools.py: 3 aspirational TODO comments from early development

tools/web_tools.py

@@ -36,10 +36,6 @@ Usage:
     crawl_data = web_crawl_tool("example.com", "Find contact information")
 """
 
-#TODO: Search Capabilities over the scraped pages
-#TODO: Store the pages in something
-#TODO: Tool to see what pages are available/saved to search over
-
 import json
 import logging
 import os