refactor: Refactor filter parsing to use comma separation and JSON values

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

src/parser/filter.pest

@@ -1,41 +1,30 @@
 WHITESPACE = _{ " " | "\t" | "\n" | "\r" }
 
-//! This Pest grammar defines the syntax for filter chains used in the Keep application.
+filters = { filter ~ ("," ~ filters)? }
+filter = { filter_name ~ ("(" ~ options ~ ")")? }
+filter_name = @{ ASCII_ALPHA ~ (ASCII_ALPHANUMERIC | "_")* }
 
-// Main entry point for parsing multiple filters separated by pipes
-filters = { SOI ~ filter ~ (pipe ~ filter)* ~ EOI }
+options = { option ~ ("," ~ options)? }
+option = { (option_name ~ "=")? ~ option_value }
+option_name = @{ ASCII_ALPHA ~ (ASCII_ALPHANUMERIC | "_")* }
 
-// A single filter with optional options
-filter = { filter_name ~ options? }
+option_value = {
+    JSON_NUMBER |
+    JSON_STRING |
+    JSON_BOOLEAN
+}
 
-// Filter name (alphanumeric with underscores)
-filter_name = @{ [a-zA-Z_][a-zA-Z0-9_]* }
+JSON_NUMBER = @{
+    ("-")? ~
+    ("0" | ASCII_NONZERO_DIGIT ~ ASCII_DIGIT*) ~
+    ("." ~ ASCII_DIGIT*)? ~
+    (("e" | "E") ~ ("+" | "-")? ~ ASCII_DIGIT+)?
+}
 
-// Options block with parentheses
-options = { "(" ~ WO ~ option* ~ WO ~ ")" }
+JSON_STRING = ${
+    "\"" ~
+    (("\\" ~ ANY) | (!("\"" | "\\") ~ ANY))* ~
+    "\""
+}
 
-// 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)* }
+JSON_BOOLEAN = ${ "true" | "false" }