fix(pwd): guard truncation-branch string ops with -- for leading-dash dirs

[Frefreak]

Description

_tide_pwd's truncation branch passes path-derived values to string match, string escape, and string join without a -- separator. When a directory component starts with -, fish parses it as an option:

• string join / string match → unknown option, the length read fails, and the prompt collapses into a cascade of test: Missing argument / math: Too few arguments errors;
• worse, string escape --style=regex $trunc inside the disambiguation while loop errors once $trunc grows to e.g. -a, so the loop never advances and hangs the prompt when a same-prefix sibling exists.

The non-truncating path already guards its two string join calls with --; the five uses inside the truncation branch were missed. This adds -- before the path-derived argument in each.

Motivation and Context

Directories starting with - are legal and occur in practice (git worktrees, tools that encode an absolute path as a slug, etc.). Any such dir deep enough to trigger PWD truncation breaks the prompt; with a same-prefix sibling it hangs the shell. Same class of bug as fish-shell/fish-shell#10169 in prompt_pwd.

Closes #668

How Has This Been Tested

Added regression cases to tests/_tide_item_pwd.test.fish covering a leading-dash directory under truncation, both without and with a same-prefix sibling (the hang case). The pre-existing --has dashes case only covered a short path that never truncates, which is why this went unnoticed.

• I have tested using Linux.
• I have tested using MacOS.

Checklist

• I am ready to update the wiki accordingly.
• I have updated the tests accordingly.

[M1nt-Ch0c0]

Automated Linux verification

I ran a targeted regression check for this PR on:

• Arch Linux
• fish 4.8.1
• PR commit 1c7b384

Results:

• Current main reproduces string join: -alfa: unknown option followed by the test: Missing argument cascade in a sufficiently long path containing a leading-dash component.
• This PR passes both targeted cases: truncation with -alfa, and disambiguation with a same-prefix sibling (-alfawolf). Both completed with status 0 and without errors or a hang.

I did not run the full test suite; this was a focused verification of the new regression scenarios. Linux side looks good for this fix.

— GPT-5.6-Sol (automated agent)

[mbolli]

Confirming this on Linux (the PR checklist only has macOS ticked).

Fedora 44, fish 4.6.0, tide main @ fcda500, running tests/_tide_item_pwd.test.fish through littlecheck in an isolated XDG_CONFIG_HOME:

1. Pristine main + its own test file: green. Confirms the point in Prompt breaks (and can hang) in dash-leading directories when path truncates #668 that the existing --has dashes case never enters the truncation branch, so the bug goes uncaught.
2. New tests + unpatched _tide_pwd.fish: fails as described. string join: -alfa: unknown option, then the test: Missing argument at index 3 cascade on every redraw.
3. This PR: green (243 ms).

One correction on the hang, in case it matters for the issue text: I could not reproduce a hang on pristine main at fish 4.6.0, with either the repro in #668 or a real-world four-sibling dash tree. Unpatched, the loop's second string match ... $dir_section also errors (rc 2), which terminates the while, so you get the error cascade but the prompt still returns.

The hang is real, but it needs the first string match guarded while the string escape --style=regex $trunc calls are not: $trunc resolves to -, escape errors to an empty pattern, and (?<trunc>.) re-matches the same first character forever. That is the state you land in if you apply only part of this fix, which reads as an argument for landing all five -- together rather than against the PR.

Hit this via Claude Code scratchpad dirs, which slugify an absolute path into a leading-dash directory name (/tmp/claude-1000/-home-user-project/...), so it is easy to reach without doing anything exotic.