fix: Resolve compilation errors for multiple definitions and parser issues

Co-authored-by: aider (openai/andrew/openrouter/sonoma-sky-alpha) <aider@aider.chat>

src/parser/filter.pest

@@ -0,0 +1,41 @@
+WHITESPACE = _{ " " | "\t" | "\n" | "\r" }
+
+// This Pest grammar defines the syntax for filter chains used in the Keep application.
+
+// Main entry point for parsing multiple filters separated by pipes
+filters = { SOI ~ filter ~ (pipe ~ filter)* ~ EOI }
+
+// A single filter with optional options
+filter = { filter_name ~ options? }
+
+// Filter name (alphanumeric with underscores)
+filter_name = @{ [a-zA-Z_][a-zA-Z0-9_]* }
+
+// Options block with parentheses
+options = { "(" ~ WO ~ option* ~ WO ~ ")" }
+
+// Single option: either named (name=value) or unnamed (just value)
+option = { WO ~ (option_name ~ WO ~ "=" ~ WO ~ option_value | option_value) }
+
+// Option name (alphanumeric with underscores)
+option_name = @{ [a-zA-Z_][a-zA-Z0-9_]* }
+
+// Option value: number, boolean, or quoted string
+option_value = { number | boolean | string }
+
+// Simple number (integer or float)
+number = @{ ("-")? ~ [0-9]+ ~ ('.' ~ [0-9]+)? }
+
+// Boolean true or false
+boolean = { "true" | "false" }
+
+// Quoted string (double or single quotes)
+string = { (dquote ~ (!dquote ~ [^"])* ~ dquote) | (squote ~ (!squote ~ [^'])* ~ squote) }
+dquote = { '"' }
+squote = { '\'' }
+
+// Pipe separator
+pipe = { "|" }
+
+// Optional whitespace
+WO = { (WHITESPACE)* }