feat(docs): add detailed planning objectives and optimization rules documentation

CONTEXT.md

@@ -83,17 +83,29 @@ The greatest number of working days in any work sequence within the planning hor
 **Short work sequence**:
 A work sequence of fewer than five working days between two planned time-off periods.
 
+**Short work-sequence deficit**:
+The total number of working days missing for all short work sequences to reach five working days each; empty sequences contribute zero.
+
 **Week with one workday**:
 An undesirable Monday-to-Sunday calendar week with exactly one working day remaining after excluding leave placements and declared non-working days. All five Monday-to-Friday dates must fall within the planning horizon.
 
 **Planning rule**:
-A user instruction that requests leave placements around a calendar opportunity or inside a date window. Its force is either an obligation or a preference.
+A named instruction, supplied by the application or defined by the user, that guides leave placement. Only enabled rules influence the plan, and each rule's force is either an obligation or a preference.
+
+**Optimization rule**:
+A preference rule that minimizes or maximizes a measure over selected planning elements, such as leave balances, time-off periods, or work sequences.
+
+**Optimization rule preset**:
+A predefined optimization rule configuration supplied by the application that the user can use as an editable planning rule.
+
+**Loss prevention rule**:
+An optimization rule that minimizes unplaced at-risk leave.
 
 **Obligation rule**:
 A planning rule that every valid plan must satisfy. Obligation rules are resolved jointly; their order only breaks ties between valid plans.
 
 **Preference rule**:
-A planning rule that guides placement but may remain unsatisfied to preserve validity or prevent more at-risk leave from expiring.
+A planning rule that guides placement but may remain unsatisfied to preserve validity or satisfy higher-priority preferences.
 
 **IF_THEN rule**:
 A planning rule evaluated independently for every French public holiday on its configured weekday. A preference requests a complete pattern around each occurrence when possible; an obligation requires it for every occurrence.
@@ -105,7 +117,7 @@ A planning rule evaluated independently for every French public holiday on its c
 A planning rule counting compatible leave placements and declared non-working days in an inclusive date window. A preference requests up to its configured quantity; an obligation requires exactly that quantity.
 
 **Rule priority**:
-The user-defined lexicographic order of preference rules. Each earlier preference is satisfied as far as possible before a later preference is considered.
+The user-defined lexicographic order shared by all active preference rules, including optimization rules. Each earlier preference is satisfied as far as possible before a later preference is considered.
 
 **Rule satisfaction**:
 The relationship in which a plan fulfils a planning rule. One compatible leave placement or declared non-working day may contribute to the satisfaction of multiple rules.
@@ -164,7 +176,7 @@ A hypothetical comparison that keeps the calculation snapshot and all unrelated
 A calculation stopped by user cancellation or another interruption before it completed the planning objective order. On user cancellation it exposes its best available valid plan as partial, if one exists, and never implies that the obligations conflict.
 
 **Planning objective order**:
-The lexicographic quality order applied after joint obligation feasibility: minimize unplaced at-risk leave; satisfy each preference in user order; maximize public-holiday week value; maximize non-working-day gain; minimize the longest work sequence; minimize the total deficit of internal work sequences shorter than five days; minimize supporting placements; consume earlier-expiring balances; then prefer earlier placement dates. Complete holiday weeks therefore precede broader calendar-gain and work-sequence optimization. A lower criterion never degrades a higher one.
+The lexicographic quality order applied after joint obligation feasibility, with active preference rules, including optimization rules, sharing the user-defined rule priority. A lower criterion never degrades a higher one.
 
 **Earned leave**:
 The total quantity of earned leave entitlements generated by all applicable planning rules for a plan, counted before consumption and attributed to their generating rules. Only entitlements becoming available strictly after the calculation's Europe/Paris calendar date qualify, including those becoming available after the planning horizon.