refactor: remove orphaned read_context_text function (Arc C) (#29)

`read_context_text` in portfolio_truth_sources.py had zero callers
anywhere in src/ or tests/ — the comment claiming "Called indirectly
via context analysis pipeline" was stale. The 5 other 0.4.0 flagged
functions (resolve_declared_operating_path, choose_primary_context_file,
render_context_recovery_plan_markdown, latest_portfolio_truth_path,
detect_boilerplate_context) all have real production callers and are
NOT orphaned.

Verified with `grep -rn` across all .py files. 2150 tests pass,
ruff clean.

Author: saagpatel

src/portfolio_truth_sources.py

@@ -293,17 +293,6 @@ def _classify_context_quality(project_path: Path, context_files: list[str]) -> s
     return analyze_project_context(project_path, context_files).context_quality
 
 
-# Utility: reads context file text, respecting size and allowlist limits.
-# Called indirectly via context analysis pipeline.
-def read_context_text(project_path: Path, relative_file: str) -> str:
-    path = project_path / relative_file
-    if not path.is_file() or path.stat().st_size > MAX_CONTEXT_BYTES:
-        return ""
-    if path.name not in TEXT_ALLOWLIST:
-        return ""
-    return path.read_text(errors="replace")
-
-
 # Utility: returns True if context quality is "boilerplate".
 # Called indirectly via context analysis pipeline.
 def detect_boilerplate_context(project_path: Path, context_files: list[str]) -> bool: