fix: remove useless f-string prefix from 144 static strings (batch 2)

[AlexFucuson9]

Problem

Strings with no {expressions} don't need the f prefix. The f-prefix adds unnecessary overhead and confuses readers who expect interpolated values.

# Before
f"Cannot read {path}"  # This is a real f-string — keep
f"Loading config..."    # No expressions — remove f

# After
f"Cannot read {path}"  # Unchanged
"Loading config..."     # f removed

Files changed (144 fixes in 5 files)

File	Changes
tools/delegate_tool.py	40
hermes_cli/completion.py	39
tools/browser_tool.py	25
agent/file_safety.py	20
gateway/slash_commands.py	20

Follow-up to PR #52254 (batch 1, 153 fixes in 3 files). Remaining ~480 hits across 40+ files in subsequent batches.

[alt-glitch]

This was generated by AI during triage.

Related: batch 2 follow-up to #52254 (batch 1). Disjoint files (this PR: file_safety, slash_commands, completion, browser_tool, delegate_tool); same ruff F541 cleanup. Not a duplicate.