Remove env reads from the provider crates

[ecalifornica]

Part of #183. Breaking change. One minor version bump and one PR per crate.

Work, per resolver

• Replace PathResolver::new() with new(home): a required home-directory argument. Delete the Default impl.
  • Stale callers fail to compile. That is the intended signal.
  • Each crate keeps the knowledge of its harness's data location (for example: claude data is in <home>/.claude). Only "what is home" moves to the caller.
• With home always present, the path accessors become infallible. Delete the NoHomeDirectory error variants.
• Where a crate builds a resolver from an override directory alone, add a from_<dir> constructor (for example from_claude_dir).
• Keep the per-crate with_* overrides, for example:

  let resolver = PathResolver::new(home).with_claude_dir("/custom/.claude");

• Add setters that take the env value, so harness layout knowledge stays in the crate:
  • opencode: with_xdg_data_home(xdg); the resolver appends opencode.
  • cursor: with_appdata(appdata); the resolver appends Cursor. Only the Windows default consults it.
  • with_data_dir and with_user_data_dir stay as full overrides.
  • copilot needs no setter: $COPILOT_HOME replaces the whole root, so the injected value carries no layout knowledge.
• pi: delete the ./.pi/agent/sessions cwd fallback.
• Delete the six duplicate home_dir() helpers.
• Delete the XDG_DATA_HOME, COPILOT_HOME, and APPDATA reads.
  • This deletes two precedence bugs: opencode reads XDG_DATA_HOME before the injected home, and copilot's env-seeded directory wins against with_home.
  • Fixes the source of Resume test suite escapes sandbox when XDG_DATA_HOME is set #169. Supersedes toolpath-opencode: capture XDG_DATA_HOME at construction #171: the env read is deleted, not captured at construction.

Work, reader flags

• Convert CODEX_ROLLOUT_STRICT, CLAUDE_CLI_DEBUG, and COPILOT_EVENTS_STRICT to parameters.
• path-cli reads each variable into Config. A bool flows inward as a builder setter on the reader type, default false.
• copilot's private read_lines_impl(path, strict) is the target shape. Delete the env read in the public read_lines.

Note

• Blocked on Add Config at the composition root #184. After it, path-cli injects all values, so this issue deletes dead code paths, plus the two live precedence bugs.

[ecalifornica]

Proposal for the override surface, so harness layout knowledge stays in one crate.

path-cli injects finished directories: with_data_dir(xdg.join("opencode")) and, on Windows, with_user_data_dir(appdata.join("Cursor")). The opencode and Cursor segments then live in two crates. When this issue deletes the env reads, the CLI joins become the only place those mappings exist.

Suggestion, as part of the env-read deletion: add setters that take the env value, not the finished directory.

• opencode: with_xdg_data_home(xdg); the resolver appends opencode.
• cursor: with_appdata(appdata); the resolver appends Cursor.

The caller passes what it owns (env values). The crate keeps what it owns (layout). with_data_dir and with_user_data_dir stay as full overrides.

Copilot needs no change: $COPILOT_HOME replaces the whole root, so the injected value carries no layout knowledge.