Unify workspace path handling in tools

[meanaverage]

This PR unifies workspace path handling across the main tool surface so the agent behaves more consistently between host and Docker-style environments.

What was fixed:

• introduced a shared workspace-path normalizer in tsunami/tools/filesystem.py
• normalized common path variants seen in traces, including /app/workspace/..., /workspace/tsunami/workspace/..., /workspace/deliverables/..., and repo-root deliverables/...
• updated match_glob and match_grep to resolve directories through the shared resolver instead of raw Path(...).resolve()
• updated shell_exec so bad workspace roots inside command strings are normalized before execution and workdir is resolved through the same shared resolver
• updated python_exec so ARK_DIR, WORKSPACE, and DELIVERABLES are derived from the configured workspace_dir instead of hardcoded ark_dir/workspace
• updated swell_analyze to remove ad hoc Docker-specific fallback rewriting and use the shared resolver for both input directories and output paths
• updated generate_image so save_path uses the same resolver instead of its own partial workspace/app/workspace stripping logic
• updated project_init guidance so the model is told to use shell_exec with workdir='deliverables/' rather than absolute-path cd commands

Why this matters:

• before this change, different tools were interpreting the same project path in different ways
• that led to runs where one tool correctly found workspace/deliverables/ and the next tool looked in /workspace/tsunami/workspace/..., repo-root deliverables/..., or another non-existent variant
• the result was repeated false directory-not-found failures even when the project actually existed

Validation:

• python3 -m py_compile passed for all modified tool modules

Important caveat:

• this PR intentionally does not modify tsunami/tools/swell.py or tsunami/tools/swell_build.py
• those tools currently use workspace_dir.parent / project-root-style working directories, and that may be intentional to preserve broader repo visibility for eddy workers
• I left them unchanged and would like explicit review on whether they should remain repo-root scoped or also move to stricter workspace-relative semantics later

[meanaverage]

Resubmitted as PR #10 for no merge conflicts