refactor: consolidate shared regex patterns and token validation

- Create src/utils/regex-patterns.ts with ANSI_ESCAPE_PATTERN_FULL,
  ANSI_ESCAPE_PATTERN_SIMPLE, TOKEN_PATTERN, and helper functions
- Create src/utils/token-validation.ts with MAX_SESSION_TOKENS and
  validation utilities
- Update session.ts, respawn-controller.ts, ai-checker-base.ts,
  ralph-tracker.ts, state-store.ts to use shared utilities
- Export all new utilities from src/utils/index.ts

Reduces code duplication while maintaining pre-compiled patterns
for performance.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/utils/regex-patterns.ts

@@ -0,0 +1,73 @@
+/**
+ * @fileoverview Shared regex patterns for terminal and token parsing.
+ *
+ * Pre-compiled patterns avoid re-compilation overhead on each use.
+ * Import these patterns instead of defining them locally.
+ *
+ * @module utils/regex-patterns
+ */
+
+/**
+ * Comprehensive ANSI escape pattern that handles:
+ * - SGR (colors/styles): ESC [ params m
+ * - CSI sequences (cursor, scroll, etc.): ESC [ params letter
+ * - OSC sequences (title, etc.): ESC ] ... BEL or ESC ] ... ST
+ * - Single-char escapes: ESC = or ESC >
+ *
+ * Use this when you need complete ANSI stripping including OSC sequences.
+ * Note: Has global flag - reset lastIndex before exec() if reusing.
+ */
+export const ANSI_ESCAPE_PATTERN_FULL = /\x1b(?:\[[0-9;?]*[A-Za-z]|\][^\x07\x1b]*(?:\x07|\x1b\\)|[=>])/g;
+
+/**
+ * Simple ANSI CSI-only pattern for basic escape code stripping.
+ * Matches: ESC [ params letter (e.g., colors, cursor movement)
+ *
+ * Use this for faster stripping when OSC sequences aren't a concern.
+ * Note: Has global flag - reset lastIndex before exec() if reusing.
+ */
+export const ANSI_ESCAPE_PATTERN_SIMPLE = /\x1b\[[0-9;]*[A-Za-z]/g;
+
+/**
+ * Pattern to extract token count from Claude's status line.
+ * Matches: "123.4k tokens", "5234 tokens", "1.2M tokens"
+ *
+ * Capture groups:
+ * - Group 1: The numeric value (e.g., "123.4", "5234", "1.2")
+ * - Group 2: Optional suffix (k, K, m, M) or undefined
+ */
+export const TOKEN_PATTERN = /(\d+(?:\.\d+)?)\s*([kKmM])?\s*tokens/;
+
+/**
+ * Creates a fresh copy of ANSI_ESCAPE_PATTERN_FULL.
+ * Use when you need a pattern without shared lastIndex state.
+ */
+export function createAnsiPatternFull(): RegExp {
+  return /\x1b(?:\[[0-9;?]*[A-Za-z]|\][^\x07\x1b]*(?:\x07|\x1b\\)|[=>])/g;
+}
+
+/**
+ * Creates a fresh copy of ANSI_ESCAPE_PATTERN_SIMPLE.
+ * Use when you need a pattern without shared lastIndex state.
+ */
+export function createAnsiPatternSimple(): RegExp {
+  return /\x1b\[[0-9;]*[A-Za-z]/g;
+}
+
+/**
+ * Strips ANSI escape codes from text using the comprehensive pattern.
+ * @param text - Text containing ANSI escape codes
+ * @returns Text with ANSI codes removed
+ */
+export function stripAnsi(text: string): string {
+  return text.replace(ANSI_ESCAPE_PATTERN_FULL, '');
+}
+
+/**
+ * Strips simple ANSI CSI codes from text (faster, less comprehensive).
+ * @param text - Text containing ANSI escape codes
+ * @returns Text with ANSI CSI codes removed
+ */
+export function stripAnsiSimple(text: string): string {
+  return text.replace(ANSI_ESCAPE_PATTERN_SIMPLE, '');
+}