docs: move remove-fuzzy-match-operator to completed

docs/features/completed/remove-fuzzy-match-operator.feature

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+Feature: Remove Fuzzy Match (~=) Operator
+
+  The `~=` (APPROXIMATELY_EQUAL) operator provides 5% tolerance numeric matching
+  in guard conditions. It is unused in practice and adds unnecessary complexity
+  to the specification and codebase. This feature removes it entirely from the
+  flowr specification, reference implementation, tests, and documentation.
+
+  Status: DONE (2026-05-06)
+
+  Rules (Business):
+  - The `~=` operator is not a valid condition operator in flowr v1
+  - Flows containing `when: { field: "~=value" }` produce a validation error
+  - The specification documents list exactly 6 operators: ==, !=, >=, <=, >, <
+
+  Constraints:
+  - Error messages follow existing FlowParseError conventions with location context
+
+  ## Frozen Examples Rule
+
+  After a feature is BASELINED, all `Example:` blocks are immutable. Changes require
+  `@deprecated` on the old Example (preserving the original @id) and a new Example
+  with a new @id. This prevents scope creep and maintains traceability.
+
+  `@id` tags are for traceability only — do NOT add priority tags (e.g. @must, @should,
+  @could) to Examples. MoSCoW classification is an internal triage step, not a Gherkin tag.
+
+  ## Pre-mortem
+
+  Imagine this feature was built and all tests pass, but it doesn't work for the user.
+
+  | Failure Mode | Risk | Covered By |
+  |-------------|------|------------|
+  | `~=` silently accepted as bare string value (implicit `==`) instead of raising error | High — user gets no feedback that their flow is wrong | @id:7aef4c1b |
+  | APPROXIMATELY_EQUAL member persists in ConditionOperator enum | Medium — dead code, potential future misuse | @id:3170064f |
+  | Spec docs or glossary still list ~= as valid operator (e.g. Guard Condition entry) | Medium — contradicts implementation | @id:817a1558 |
+  | ADR left without deprecation context — future readers don't know ~= was removed | Low — documentation hygiene | @id:452ceae3 |
+  | Glossary "Fuzzy Match" entry not marked retired (append-only glossary) | Low — glossary convention, not operator table | In scope of implementation but not a separate Example; covered by 003's scope including glossary.md |
+
+  All failure modes have corresponding Examples. No additional Examples needed.
+
+  ## Questions
+
+  | ID | Question | Status | Answer / Assumption |
+  |----|----------|--------|---------------------|
+  | Q1 | Should ~= produce a specific error or fall through to implicit ==? | Resolved | Clear parse error following FlowParseError convention |
+  | Q2 | Should we supersede the ADR? | Resolved | Add deprecation note to existing ADR only |
+  | Q3 | Should docs/index.html be updated? | Resolved | No, out of scope (already omits ~=) |
+
+  ## Changes
+
+  | Session | Q-IDs | Change |
+  |---------|-------|--------|
+  | 2026-05-06 S1 | Q1-Q3 | Created: remove ~= from code, tests, spec docs, ADR |
+
+  Rule: Remove ~= operator from specification and implementation
+    As a flow author
+    I want the ~= operator removed from the flowr specification
+    So that the specification is simpler with only operators I actually need
+
+  @id:7aef4c1b
+    Example: ~= operator is not recognized
+      Given a flow file with `when: { score: "~=100" }`
+      When the flow is loaded
+      Then a FlowParseError is raised indicating ~= is not a valid operator
+
+  @id:3170064f
+    Example: ConditionOperator enum has 6 operators
+      Given the ConditionOperator enum
+      When its values are listed
+      Then it contains exactly EQUALS, NOT_EQUALS, GREATER_THAN_OR_EQUAL, LESS_THAN_OR_EQUAL, GREATER_THAN, LESS_THAN
+      And does not contain APPROXIMATELY_EQUAL
+
+  @id:817a1558
+    Example: Specification documents list 6 operators
+      Given the specification documents (flow_definition_spec.md, glossary.md, product_definition.md)
+      When the operator list is checked
+      Then exactly 6 operators are listed: ==, !=, >=, <=, >, <
+      And ~= does not appear in any operator table or definition
+
+  @id:452ceae3
+    Example: Fuzzy match ADR has deprecation note
+      Given ADR_20260426_fuzzy_match_algorithm.md
+      When the document is read
+      Then a deprecation notice is present indicating ~= has been removed from the specification